Since the late 19th Century, long before the first U.S. Geological Survey (USGS) office was opened in Wyoming, USGS scientists have been investigating the geology and water resources of the State and publishing their findings. The main product of all USGS work in Wyoming comprises the published reports of those investigations—mostly maps and book reports of the USGS, but also articles in scientific journals, guidebooks, conference proceedings, and publications of Wyoming State agencies. This bibliography was last updated in 2008.