from fort pierce, florida.uest: it is interesting, truman had a secondary white house in key west, florida, which is actually still there and gives tours. but i did not know about the kennedy situation. i wish i could help you about grant. i don't -- there is no library that i know of of grant. the libraries, the most for they have become -- most retroactive they have become is going back to hoover. i understand amity shlaes was talking about this a little while ago, you can visit calvin coolidge's home, but it is not a presidential library, in a sense. even with the access to materials that we are talking about here. i think it is a phenomenon in the post-world war ii era and has become more and more gargantuan, in the sort of presidential presentations. host: we have talked about the purpose and the collections themselves. i want to talk about who visits these libraries and why. and to do that, this has been -- this is from the harry s. truman library and museum, a series of interviews that they put together

alan is at fort pierce, florida. good morning. caller: good morning. thank you, c-span.his is such a wonderful program. i like so many programs on c-span, and especially the ones about the presidents. a couple of comments. i think the portrait gallery is a wonderful place to see the portraits of the presidents. i was a little bit surprised that there was only one small photograph of julia dent grant in the portrait gallery, and i do not know why that is. i do not know if there are other portraits or pictures of her at the grand presidential library. maybe mr. rothstein, you could talk about that? another comment, i have read so much about hyde park that i would definitely like to get up there to see that. and most recently -- i live in florida, and to the south in the palm beaches where the kennedys used to spend some time in the winters, and there is a place that is being restored in the lake worth lagoon that was a bunker that was built for kennedy should there be any kind of problem or disaster, and now there is a group that is trying to restore the bunker on a place

a research professor at florida atlantic university's harbor branch oceanographic institute in fort pierceook us on a three-hour tour of the lagoon. dennis: it's definitely a lagoon in peril. miles: we were hunting for seagrass. the average adult manatee forages about 100 pounds of it every day. but all we saw was a lot of algae, which blocks sunshine from reaching seagrass rooted at the bottom, killing it. dennis: so, we probably have lost at least 80% of the grass, but there are many areas where there's zero seagrass, i mean, 0%. 2011, when we started the blooms, that's really when everything did the catastrophic decline. miles: a huge algae bloom in 2011 was just for starters. ever since, recurring algal events known as brown tides have pushed this rich ecosystem out of balance. in 2016, a brown tide starved the water of oxygen enough to trigger a massive fish kill. the problem has grown along with the human population around the lagoon, now more than 1.5 million, an increase of 50% in the past 25 years. today, there are more than 300,000 septic systems in the six adjacent counties, and

alan is out of fort pierce, florida. you are on with edward rothstein. caller: good morning.c-span. such a wonderful program. i like so many programs on c-span and especially like the ones about the presidents. i think the portrait gallery is a wonderful place to see the portraits of the presidents. i was surprised there was only one small photograph of julia grant in the portrait gallery. i do not know why that is. i do not know if there are other portrait or pictures of her at the grant presidential library. maybe mr. rothstein could talk about that. i have read so much about hyde park and would definitely like to get up there to see that. most recently -- i live in florida and in palm beach is where the kennedys used to spend time in the winters. there is a place that is being restored in the lake worth lagoon that was a bunker that was built for kennedy should there be any problem or disaster and now there is a group trying to restore the bunker on peanut island in the lake worth lagoon. if you could comment about this i would appreciate it. host: thank you for the call.

alan is at fort pierce, florida. good morning. caller: good morning. thank you, c-span.is such a wonderful program. i like so many programs on c-span, and especially the ones about the presidents. a couple of comments. i think the portrait gallery is a wonderful place to see the portraits of the presidents. i was a little bit surprised that there was only one small photograph of julia dent grant in the portrait gallery, and i do not know why that is. i do not know if there are other portraits or pictures of her at the grand presidential library. maybe mr. rothstein, you could talk about that? another comment, i have read so much about hyde park that i would definitely like to get up there to see that. and most recently -- i live in florida, and to the south in the palm beaches where the kennedys used to spend some time in the winters, and there is a place that is being restored in the lake worth lagoon that was a bunker that was built for kennedy should there be any kind of problem or disaster, and now there is a group that is trying to restore the bunker on a place call