2006. Rawson, Peg. This point shapefile depicts major dams in the United States, including Puerto Rico and the U.S. Virgin Islands. The map layer was created by extra... United States. Bureau of Transportation Statistics.
2013. Institute for Water Resources (U.S.). Navigation Data Center. This point shapefile contains the locations of waterways locks in the United States. The Navigation Data Center had several objectives in developin... United States. Bureau of Transportation Statistics.