tour staff recently traveled to las vegas to learn about its rich history. learn more about las vegas and other stops on our tour at c-span.org/citiestour. you are watching american history tv all weekend, every weekend on c-span3. >> on lectures and history, university of colorado boulder professor sutter talks about how the rise of commercial fertilizer affected trade and farming practices. in the 1800s, farmers looked for nitrates to enrich their soil, and moved away from traditional methods, such as field rotation. his class is about 50 minutes. prof. sutter: my name is paul sutter, i am a professor here at the university of colorado, boulder. this is an introduction to global history.

today, our lecture is on agriculture and the fertilizer revolution. we began this course talking about agriculture with regards to the unending frontier, the expanding across the world, and the birth of the plantation complex in tropical regions. another critical storyline and the environmental history of agriculture has been agricultural intensification. the growing, intensifying land-use to get more crops out of those lands. this coincides with the industrial revolution, which created a real need for those in europe and the united states to really concentrate on increasing food production to escape the trap, thinking that population would grow faster than a food production.

there was the green revolution, where modern agriculture and genetic engineering was introduced to the developing world. today i want to talk about the 19th century and the fertilizer revolution. in a most general sense, a shift away from close to systems of agriculture, soil fertility was raised within the farms and various ways. and we will talk about that. it was changed to a and open system where concentrated forms of soil fertility were imported into the farm. they were mined and brought out to the farms, used intensively, and would pull nutrients off the farm, out of soils, and away from the land. this became an open system of nutrient cycling. i want to use this term, i got this also from karl marx. by metabolic rift i mean a break

in the chain of nutrient cycling first on the farm and then between the city and the countryside. with traditional sources of fertilizer becoming waste and new sources of fertilizer needed. what we will see then is the industrialization of soil fertility. the transnational story, i will tell it that way, with a focus on the united states. before talking about that, let's step back for a minute and look at what soil and soil fertility is. soil is one of the most important natural resources. it is the result of several processes. the first is simply the breakdown of what is called parent material like rock and sediment into loose matter that provides minerals for plants to grow.

the second is the breakdown of organic material which combines with this broken down parent material and gives soil its physical, neural structure. finally, recognize soil as a living thing. there are all sorts of insects, worms, microorganisms at work in soil that are critical to plants and crops' growth. soil characteristics are biological, physical, and chemical. plants need all sorts of things to grow, it is pretty basic. they need sun, water, carbon dioxide. but they also need nutrients, macronutrients in particular, like nitrogen, phosphorus, and potassium, the holy trinity of effective fertilization. they also need micronutrients, we won't talk about those as

much today. most macronutrients come from the breakdown of soil, but the most troubling one would be nitrogen. that is at the heart of today's story. let's talk about the nitrogen cycle, i know this is a history class, but it turns out it undergoes a dramatic historical change during this period. it is a cycle of nitrogen between land and atmosphere. this is worked out largely in the 19th century. before that, people did not fully understand the nitrogen cycle. we now know the atmosphere itself is about 79% nitrogen. that atmospheric nitrogen is a critical source of nitrogen for plants and plant growth. but it is not immediately available to plants. and this is the most critical point we have to make, it is locked up in this n2 at him. they cannot breathe nitrogen, so

it has to be made bioavailable to them. i think we talked a little bit about this before. one is a lightning, which can fix nitrogen in the soil, that is an unimportant part of the cycle, but worth knowing. the other two ways are by soil microorganisms. some of which are symbiotic with a type of plant called a legume. they have the capacity to pull nitrogen out of the atmosphere and put it in the soil in ways that make it available to plants. to the planting of leguminous plants like peas, soybeans, peanuts, black-eyed peas, lentils, these were all crops that have the capacity to fix nitrogen from the atmosphere

into the soil. there are also non-symbiotic bacteria that can do this, as well. but legumes are critical. the earth has a natural nitrogen cycle, nitrogen is constantly cycling in the atmosphere and in the soil. it is a result of decomposers, taking bacteria, and denitrifying bacteria. bunnies apparently help in this process. [laughter] what i want to emphasize, one of

the products of the metabolic rift i referred to, is the human transformation of the nitrogen cycle into the 20th century. that may not make a lot of sense to you right now, but i promise i will get to it and explain it in some detail. but we're getting ahead of ourselves. let's talk about the critical problem here, how do farmers over time maintain soil fertility on the lands they are farming? and before we get to this fertilizer revolution, i want to suggest a of ways in which they did that. perhaps the most important, early on, was shifting cultivation. by shifting cultivation, the dominant mode of fertilizer management worldwide. it was an approach whereby farmers would clear it a piece of land, usually for us, usually using fire to burn off and make nutrients from organic material immediately available. it turned out that the fire and the ash produced has a basic ph

which could correct for acidic soil. farmers would then farm that cleared land for a certain period of time, taking advantage of the natural fertility in the soil. when the fertility began to wane, farmers would move on and clear a new piece of forest and let the oldfield revert back. they might come back around to it, but decades later when it had regrown backup and restored its capacity to be fertile as a result of that regrowth. practice on a small scale, was reasonably sustainable, and not that damaging, ecologically. though it was and still is a land-intensive way of farming. it required a lot of land. another way to think of it, for the little piece being farmed at

any moment, there has to be a lot of land available so the farmer can then migrate. does that make sense? that was one of the most important ways in which farmers managed soil fertility in the past. and typically in tropical regions. we will talk about why that is the case in later lectures. turns out tropical soils, burning is a good match for them. having focused on slash and burn as a strategy, a tremendous number of american farmers also practice this, particularly in the american south. that was where plantation crops were grown like tobacco and cotton. farmers would farm the land until its productivity was worn

out, and then they would move on. this actually created a caricature of the southern farmer as a soil-mined. someone who did not care for the land, went out and cleared the land, took the nutrients out -- of course, they were growing staple crops like tobacco and cotton -- they would mine the nutrients and then move on. a lot of agricultural farmers and others who valued the stable, sedentary agriculture saw this as a particularly slovenly or wasteful -- they would not say destructive, but that is what they meant. there was an attachment in places like the american south to being more settled and civilized. and his brand of agriculture seemed messy.

it actually seemed a lot like native american agriculture. they practiced slash and burn cultivation for the most part. also, forest fallow. a farmer might own thousands of acres of land, but only farmed a little at a time. that farm base was there so they could cycle their arable land throughout a 20 year cycle. it did not look good, but it was potentially sustainable. and of course, this land use and soil fertility management system, combined with slavery in the south, southern farmers were particularly interested in maximizing their investment in slaves.

to do that, they had to get as much productivity out of the land as possible. in the context where there was a lot of land to be had, and there was not a lot of labor to be had. there was an economic logic rooted in slavery to the alliance upon shifting cultivation of the strategy first soil fertility management. clear so far? questions from anyone? i will charge more to the interesting stuff. another way of managing soil fertility, i will mention this quickly and move to another system. it is to manure. what do usually think of, when you hear the word manure? animal manure. i include fallowing here, you would farm a field for a while

and let it rest. probably not enough for agriculture to be sustainable. a lot of farmers required ground manure. but also nightsoil, and human waste. also, organic materials near the ocean, seaweed, leaves from the park. also, the use of cover crops and legumes, sometimes plowed into the land. all these were important to return nitrogen and other macronutrients to the soil. but there were two things about them farmers did not always love. one, they were labor-intensive. if shipping was labor-intensive, applying manure was, too. it did not allow for the

maximization of one land for commercial production. that is an important point. it did allow for agriculture to be a more land-indeterminate thing. with this model of soil fertility management, we see in great britain across the 17th and 18th centuries, and emerging revolution that allowed for much more intensive agriculture on set pieces of land, sustainable over the long-term. i will explain this quickly, it is complicated. it involves replacing fallowed land, land out of production, replacing it with improved pasture. pasture grasses, some of which were luminous. they were used for human and animal consumption, and grain and other marketable crops. and then pasture.

the idea is that you're devoting a substantial part of your form to growing things the animals are going to eat. that animal digestive process will produce a really high-quality maneuver, especially if you're using turnips. farmers became very careful stewards of this manure, dung, as they called it. it allowed them, effectively, to within the bounds of a permanent, settled farm, raised efficient soil fertility as livestock manure to keep those farms producing indefinitely. they would move pastors to farmland to clover, and rotated through the farm, so the

nitrogen-fixing of the clover would be used for grain farming later on. this was a very effective system, called convertible husbandry. it managed to retain soil fertility really effectively. but it was incredibly labor-intensive. it meant that only a small portion of one plant at any given time could produce crops for market. for those reasons -- there is actually a reform in the american south of that tried to get southern farmers and planters to raise more livestock and improve their pastors, and to produce high-quality manure in a way that would allow them to settle in place, and not be constantly engaging in shifting. it did not work, because they were more interested in using fresh land to produce big crops of tobacco and cotton and maximize their capacity to

market these crops. nonetheless, this was a really important, and pretty powerful way, of raising soil fertility in a closed system. this became the best model of the western world for a closed system for fertility maintenance. now we will look at how the system gets cracked open. before doing that, i want to take a quick digression, and that is what happens to fertility management as people urbanized more and more. as more and more people are concentrated in urban areas, urban areas themselves become places that have a lot of organic nutrients that need

recycling. that happens in a variety of ways. one, this might be from great britain, a figure known as the rag and bone man, they would go around to household and collect any rags that people might have, or bones, as a result of cooking or slaughtering livestock. do you know what the rags were used for? rags were the critical resource for papermaking in the 19th century. papermaking relied upon rag recycling, but the bones were used for fertilizer. these folks would aggregate huge collections of rags and bones. this is a photograph from baltimore, a figure called the

nightsoil man. he would go around and collect human waste. this was before there was indoor plumbing, so all of these wastes were collected in privies. it was perhaps not surprisingly, that this is an african-american worker. this worker would collect the wastes and take them to the countryside. i will show you that in a minute. do you know what that is? this is a street scene in lower manhattan. this is horse manure, one of the greatest sources of fertility. and all of these things, nightsoil, bones, horse manure, would be brought out into the

immediate hinterlands, and be dumped on the farmlands. places like long island, brooklyn, queens, those were agricultural hinterlands in new york's early history. they would produce a lot of crops for urban consumption. and they would get the urban waste recycled back to their land. not a metabolic rift. but let's move in that direction. one last thing. anyone know what this is a picture of? >> american bison. prof. sutter: yes. these are bison bones. people hunted bisons on the american planes almost to extinction. when the bison were all but gone, commercially extinct, the next industry that hit the great

plains was an industry to collect bones, which were then ground up into fertilizer. the question? >> is the bison species extinct? prof. sutter: no, it is not. but it was the subject of intense market hunting. there were so few left, there was a growing conservation movement to keep them from going extinct. and now they made a big comeback, although a lot of the bison we see, are crossed with cattle, so they are beefalos. there is a genetic mix there. that gives you a sense of how important bones were to the fertilizer trade. a quick scientific foray. soil science is also critical to the story. i won't bore you with too many details. coming into the 19th century, scientists believed in the humus

theory of soil fertility, the idea that it was fertile because of the organic matter and manures that breakdown into it. this is a model of soil fertility that i think anyone is spent time doing organic farming would be familiar with. it made a bit of a return. but this man, a german chemist, challenge this and opted instead for a reductive soil chemistry that began to argue that fertile soils relied upon a couple critical nutrients. nitrogen, potassium, phosphorus. there will be a three number ratio, the ratio of those three elements. he is one of the ones that encourages us to think of fertilizer as more like vitamins then food.

the humus theory saw soil as something that needed to be fed. but no, it needed in fusions of these chemical, mineral elements. nitrogen would be the trickiest one. but as luck would have it, just as liebig was writing his major treatise on the subject in 1840, and industry was beginning to capitalize on a remarkable new sort of concentrated, mineable, nitrogen, that came from an unlikely, remote place. these islands called the chincha islands.

anyone know where these islands are? >> i would like to ask where these islands are located? [laughter] prof. sutter: anyone know? >> they're located off the coast of peru. prof. sutter: i will show you a map later. it is a very small island, three of them granite, off the coast of southwest peru. best known as hosts for massive colonies of sea birds, cormorants, pelicans, who would come to these islands, and had been for hundreds of not thousands of years, urinating and defecating on these islands in huge numbers. i have to give you a sense of

the magnitude of this because it is actually quite staggering. in some places, and we will see some pictures, people who came to mine these deposits found them to be about 150 feet deep in some places. how could this be? a couple things important about the ecology of these islands, there was the humboldt current that brought nutrients out of the deep sea water and up to the surface, which fed small fish, in this case, anchovies. huge schools of anchovies around there which allowed the sea birds to feed without abandon on them. and they process this fish fertilizer throughout their digestive tract. the islands also exist in a rain shadow from the andean mountains. they get about one inch of rain fall a year. why is that important?

>> no rain shadow means there was no chance to wash it away to get harvested. prof. sutter: in this case, the lack of rainfall effectively means there is no washing away or leaching of this. in most other places, bird guano would've been washed away or leached away. these are almost pure, geological deposits of bird crap. they were used by peruvian native people for hundreds of not thousands of years. the great question then humboldt asked, when he made note of these deposits and took peruvian quando back to him with europe where he had chemists tested and found it was incredibly rich in nitrogen.

the first deposit to the united states, by order of the editor of "the american farmer," in 1824, and within decades, as others confirmed guano's fertilizing power, and international trade was developed in peruvian guano. a hugely important thing. sorry, i am a little behind there, there is my slide. as always, i will post these, so if you do not get a chance to jot these down now, they will be here. here are early illustrations of these islands. these are, effectively, guano deposits.

if you don't believe the etching, there is another one. i will show you some photographs in a minute. alexander von humboldt, brought it back. they are light and easy to transport. so unlike manure or nightsoil, it comes in a light, easy to transport package. another part of the story that is important to understand, to mine these guano deposits would be incredibly awful work. have any of you ever cleaned out a chicken coop? magnify that about 100 annual get an idea. this guano was incredibly acrid and dusty and get into people's lungs and make them sick. it was not work anyone wanted to

do. not surprisingly, the earliest guano farmers were slaves. peru outlawed slavery in the 1850's, and it was increasingly fed by a trade in chinese labor. some of it coming from the fujian coast. about 100,000 laborers from china, semi-free labor was brought to peru. many of them ended in the chincha islands where they had to work off the cost of their transport, mining guano. it was awful work, they got paid very little. it was defeated the fertility revolution in the developed world. it is also a story about the

decline of slavery and the rise of other types of global labor and migration. suicide was also a really major problem, particularly among the chinese workers, who often kill themselves because the work was so awful. here's a look at one of the sheds, and the deposits. these are people here with guano carts there filling. they would then put them in these canvas chutes, to take to the united states and europe. between 1840 -- there is an ad for pacific guano. and just a look at the period of kuan no export, really peaking and 1870's. a little decline there, and then going down again after that. in this period, exports were

more than 12.6 million metric tons. talk about mining. think about this in relationship to our lecture on coal mining. there is a real analog here between tapping into these fossil forms of soil fertility and the shift in organic to fossil fuel regime. the peruvians retained control of the islands, but it was dominated by british trade houses, w.j. myers out of liverpool, and another ad from london that had a motto applied to them, "the house of gibbs made its dibs selling the turds

of foreign birds." it was almost certainly the case that the potato blight that would undo the irish potato crop in 1840's and prompting massive wave of irish immigration, would walk from south america to europe. there is another little interesting tidbit of the columbian exchange. a lot of this guano was sold to french sugarbeet farmers. but probably half of it went to british agriculture to help grow food for the industrialization of britain. about a quarter of it went to

the united states. not surprisingly, a lot of it went to the american south, to help restore the fertility that some planters had worn out. increasingly, the importance of guano to american farmers led to political calls to break the peruvian monopoly. president fillmore, one of the less memorable presidents in our history, dedicated a substantial part of his annual address, the state of the union, in 1850, to the need for the united states to find strategic guano reserves. it was to mid-19th century politics with oil is today. in 1856, and i should get my slide here, congress passed the guano islands act of 1856. what this act effectively did, it allowed american citizens who might be searching for new guano

islands in the pacific or caribbean, if they found a new islands covered in guano, and/or otherwise unclaimed, to claim these islands a sovereign territory of the united states. the guano islands act of 1856. and this huge guano island rush. most of the other guano islands had much smaller deposits and were much less rich in nitrogen because of rain leaching. nonetheless, there was a rush to find it. this is a bit of a digression, it did not articulate comfortably with the u.s. system

of incorporating into nations. westward moving americans usually would settle a territory, and it would be incorporated into the nation as a territory and then estate. but these guano islands would never become part of the united states like states. they would just be islands connected in formally. let me read the language of the act. whenever a citizen of the u.s. discovers guano not within the lawful jurisdiction of any government or occupied by the citizens of any other government, and takes peaceable possession thereof and occupies, such an island may, at the discretion of the president, be considered as appertaining to the united states. that phrase, appertaining, would be absolute critical at the turn

of the 20th century when the united states becomes a colonial nation. when it takes some colonies like the philippines, guam, puerto rico, etc. it does not create mechanisms allowing them to become part of the united states. there are a series of supreme court cases, insular cases, that create the legal justification for the taking of colonies. and what others rooted in? the guano islands act of 1856. at any rate, guano is hugely important for these industrial centers in the united states and europe. eventually it plays out. the search for concentrated nitrate fertilizer shifts to another really interesting

place. in this case, a place called the atacama desert in chile. anyone been there? >> it is one of the world's highest deserts, and one of the driest places as well. prof. sutter: is one of the driest places on earth, that is important. it has incredibly rich sodium nitrate deposits, nearly pure. a rock-like layer found under a gravel surface. very quickly, this becomes the next site for mining nitrate fertilizer. it was mined here by peruvians, bolivians, and chileans, and

there was debt-peonage labor. it was mostly underwritten by british and american capital. a man became known as the nitrate king and dominates the system, owning 70% of the industry. these chilean nitrates effectively replaced peruvian guano, and they also rely on huge numbers of jute sacks, most of which are grown and processed in bengal. this slide is a little blurry, but the atacama desert is here. and like the chincha islands, it is the andean rain shadow that makes for the rich ecology.

most of these nitrates went to britain and germany. in the united states, they particularly said the growth of the citrus industry in california. chilean nitrates going up the pacific coast and feeding california agriculture. the nitrates trade would last into the 1930's. i think i have a similar slide here. this is from a great article by a scholar, gives you an idea of the spiking in the early 1930's. i will explain that cut off in a minute. >> were companies and governments actively looking for these huge deposits of nitrates,

or just stumbled upon them? prof. sutter: a combination. i quickly went through that story about urban fertilizers. one of the important things about that, horse manure, nightsoil, bones, that created a fledgling commercial fertilizer industry and got people in the habit of thinking about fertilizer as being something they don't necessarily raise on the farm but can purchase in commercial marketplaces. those supplies, like bones from bison, proved increasingly inadequate. people looked elsewhere to find those things. i focused particularly on nitrates, but phosphates are analogous, but slightly less interesting. some of it was stumbled upon. some of it was urban trade at

cause people to think about fertilizer as a commercial commodity. some of it was liebig and is reductive chemistry. eventually people said, we know we need nitrogen, where can we find it? under the humus theory, this approach might not have made quite as much sense. does that answer the question? good question. in the u.s. south, they did not use a tremendous number of chilean nitrates. we will see some ads, european. they ended up shifting to a different source of fertilizer. this is a fish called the menhaden. it is like an anchovy, a very

small fish. it is a plankton feeder. it exists in huge schools in the atlantic ocean. today, does anyone know what it is harvested for today, it is controversial? there is a company called omega that harvested these for fish oil, or supplements for human ingestion. early on, menhaden came to replace wales as whales were increasingly extinct or hard to find as a major source of oil. once at oil was pressed out of them, and they are fish that are not good for eating, their bony and oily. once they were pressed, they

became an important source for commercial nitrates. now we are mining the seas defined nitrogen fertilizer to feed, mostly tobacco and cotton farming. still one in which very poor southerners are trying to bring crops of cotton from increasingly degraded land. usually they are in land, one of the reasons, because they are buying a lot of fertilizer. also, phosphate fertilizer being mined from south carolina, and later, tennessee. any questions? >> how long did they use the menhaden fertilizer? prof. sutter: they still do, to a certain degree.

the end of my story would shift that menhaden fertilizer to animal feed. it was increasingly necessary for fertilizer, because of these. these two guys are fritz haber and carl bosch. he told his superiors in germany that he had perfected a reaction capable of generating ammonia, creating -- he had figured out how to mine the air of nitrogen. and carl bosch standardize it into an industrial process. we know it as the haber-bosch.

mining this from the air began in 1913. what else are nitrates used for? >> explosives, like for a war. prof. sutter: munitions. we were just about to enter into world war i. this process would prove really critical to the german capacity to fight world war i. after world war i, there were all these industrially produced nitrates hanging around as farmers would then begin to turn to them. after this long search around the globe for nitrates, we have a fully industrialized process for producing nitrogen.

the haber-bosch process after the 1930's, and incredibly energy-intensive process, we would not need guano or menhaden anymore. at least for people who could afford it. this brings to a conclusion these various metabolic rifts occurring throughout this period. i talked about the urban fertilizer market. what happens to the rest of the world with the use of nightsoil and horse manure? they cease to be so organic, increasingly we have indoor plumbing, that takes our waste away, where these critical nutrients become what we call pollution. we also cease to have so many horses in cities, and cease to have the manure problems as well.

another one was having to travel the world over to find these concentrated forms of nitrogen pollution. let me end by pointing out, sorry again, a slide behind, how the haber-bosch process transforms the nitrogen cycle. today, industrial nitrogen fix asian through the haber-bosch process, produces about 32 million metric tons. of the intentional contribution of legumes -- we also get nitrogen oxide from bosch, another 25 million metric tons. combined, and you can do the math here, we are looking at about over 157 million metric tons but a human produced.

the natural nitrogen cycle itself only cycles about 110 million metric tons between land and air. so the human nitrogen cycle has become bigger than the natural one. >> what industrialization would that affect, the changing diet, outdating nightsoil -- with the change of the diet of people during industrialization, would that change the viability of nightsoil? prof. sutter: all of this fertilizer would be critical to raising the foods that support one of the other critical things, the huge bison population growth.

in the 19th century, this kind of fertilizer was being used only in very particular paces. the vast majority relied upon shifting cultivation or our gannett nutrient cycling, some manure. increasingly they turned to this. what you get is a result, my final slide. this is a map of the mississippi-missouri watershed, which has become a huge source of nitrogen pollution. all of which runs downstream and has created a hypoxic dead zone. nothing can live in the gulf of mexico here because so much nitrogen fertilizer is being pushed into the gulf, creating huge plankton blooms, sucking all the oxygen out of the water.

i will just leave you with a bat, in terms of what the end result of all of this is. last question, because we do have to end. >> what sort of long-term solutions do they have for this? can they remove nitrogen from the water and restore it, while also reusing the nitrogen? prof. sutter: my understanding, that is very difficult. it would be a very energy-intensive process. it is important to get pharmacy is nitrogen and away less likely to leech large amounts out into aquatic ecosystems. all right, thanks all, see you next time. >> you are watching american history tv. 48 hours of programming on american history every weekend on c-span3. follow us on twitter for

information on our schedule and to keep up with the latest history news. weekend, american history tv is featuring las vegas, nevada. its home to the stratosphere, the tallest freestanding observation tower in the united states at 1149 feet. our staff recently visited many sites showcasing the city's history. learn more about las vegas all weekend here on american history tv. >> i think classic vegas means certain things to certain people. century 20th century was about as classic as it comes. you were talking about sinatra, sammy, dean, the rat pack, the

bright lights, the shows, the gambling, even organized crime. all of that is encapsulated right here. i like to say in the city of a lot of magical places, this is probably the most magical. >> classic las vegas is one of those eras when las vegas really defined itself as different from anything else in the united states. las vegas was a little town in the middle of the desert. it had really functioned because of feral funding. with the end of world war ii, that was gone so it had to become something else. what it chose to do was advertise itself as a place to have fun. world war ii and the depression before that had really stopped a lot of people in the united states from being able to do anything. they were just getting by, trying to survive. with the end of world war ii, you had people coming back from the war.

they were going back to school, getting out of the military, out of this regimented lifestyle. they can now buy cars, travel, get whatever they needed. and, they wanted to let off steam. they wanted to be able to do something fun. las vegas was here. play by day, play by night. seeing great entertainment throughout the strip, whichever property you were in, you had live entertainment in the lounges. you have the shows you would go to, good food. you also had gaming. we allowed you to spend your money here. that is what underwrote it. all of the properties, the casinos on the strip, what they were trying to do was attract the eyes so you would drive into their parking lot. the casinos in the 1940's and 1950's were two or three stories tall. they looked like fancy fronts on a motel. it is not what we think of today

, 30, 40 story buildings. that was all on a human level, a ground level, and so you had to have signs and imagery that would draw you in. hugead a lot of lights, signs. nhe champagne tower or aladdi standing on top of one of the buildings. the silver slipper with a giant silver slipper in the air. all the sings were meant -- signs were meant to draw the eyes. you could just but the name out there and have a wooden board and paint the name on it. that was not it. you wanted this bright movement and the sign. the signs took on a hugely important role in the advertising of the properties and the drawing of people into the properties.

>> it is made up of about 200 neon signs. we started this collection about 20 years ago and finally opened into a full-blown museum with a visitors center about three and a half years ago. the popularity of the museum has been absolutely overwhelming. we have had visitors from 60 countries, every state in the united states. so there is a real appetite for this type of museum. ort of tells the story of neon and las vegas. neon evolved in the 1920's and the 1930's and really took off in the 1940's. what you could do with neon and ubes intois bend the t spectacular images. then, you could like those tubes with all different kinds of colors.

then, when you combine the neon with the lightbulbs and the canisters of the signs, you basically came up with not only a sign, but a work of art. when las vegas started imploding all of its old hotels to build a new hotels, we look at this and said, hey, this is art. it is art and history. we need to keep it for generations to come. because of the cost of the signs and the cost of restoration, we will not be able to restore all of the signs and we would not want to because we love this boneyard, this museum and it has its own vibe. there is a plan to restore multiple signs that would be a

long las vegas boulevard leaving from the museum on the way towards sahara avenue. they are very expensive to restore and to move. the largest sign in the collection is the stardust sign. it is 15 stories high. it was cut into eight pieces when it was moved and it cost a quarter of a million dollars to move it to the boneyard. we just restored the desert rose motel sign. it stood where mandalay bay is now located. it is a very small sign. it was not a full restoration effort. it was really the first one that was a conservation effort here. while the neon tubing was not completely restored, we preserved other portions of it like the lattice work, the red roses, the pain. t. that by itself was $60,000.

jobcan see how immense the is when you talk about a complete restoration of any sign. we actually have several signs that are lit up in the boneyard. i believe we have seven. it is interesting because a lot of people like to come at night and see the ones that are lit that have a different feel to it jus like daytime. others like to come during daytime because you could really see more of the design, the artwork, what really went into making the signs. you sort of have two choices which makes it kind of fun. when the strip started in the 1940's, there were 7000 people in the las vegas valley. there is now 2.1 million people that live here. las vegas has not been really good about respecting its history. i think, as i have mentioned before, we have torn down a lot of iconic hotels. as we have torn down these

midcentury beauties and they were beautiful hotels, i think it is important that we save at least some remnant from those hotels. we think it is important that we need to protect our history, how did the city come about and what better place to do it then in the neon boneyard? our cities tours staff recently traveled to las vegas, nevada to learn about its history. what about other stops on the cities.o to c-span we were watching "american history tv," all weekend every weekend on c-span3. history bookshelf, elizabeth professor at the university of virginia, talked about her book "appomattox