U.S. Geological Survey
Created by an act of Congress in 1879, the United States Geological Survey (USGS) is a scientific agency under the U.S. government whose purpose is to investigate, survey, and map the United States territory, including natural resources and any potential threats to the depicted habitat. The organization has evolved over time, gradually adapting to the progress of science and technology.
The USGS is the only science-based agency under the Department of the Interior, and its responsibilities fall within the disciplines of biology, geography, geology, and hydrology. The USGS is considered the best authority on domestic questions relating to these subjects, and often their maps will cover several or all of these themes in the same chart.