. >> reporter: anna darr isn't sure exactly where the speed camera was. >> well, i admit that i was speedingi was going approximately 40 miles an hour. >> reporter: her fine, $110. 150 communities in 13 states now use speed cameras. some are stationary, some are mobile. and no city has embraced them more than washington, d.c., where more than 90 speed and red light cameras are spread across the city. police chief kathy lanier. >> just the shear impact it's had on reducing traffic fatalities in my opinion has made it worth every penny of investment. >> reporter: in d.c., traffic deaths have dropped from 70 ten years ago to just 19 in 2012. speed, say researchers, plays a role in a third of all traffic fatalities. >> it's not just speeding on high speed roads. it's speeding on city streets, arterials, across the board. >> reporter: okay, full disclosure, this speed camera in washington, d.c., got me. according to my ticket, i was doing 38 in a 25. my fine? $92. it turns out this is washington's busiest camera, generating more than $8 million in ticket revenue this year alone, but even though 5