The U.S. Census Bureau is the agency that provides the U.S. Gazetteer files. These files contain information about geographic locations and features in the United States. They are used for various purposes, including geographic planning and analysis. The Census Bureau's website offers access to these files, which can be downloaded for use in Geographic Information Systems (GIS) and other applications. The U.S. Geological Survey (USGS) also provides related geographic data through its National Map Gazetteer, which serves as a national standard for geographic nomenclature. For more detailed information, you can visit the U.S. Census Bureau's Gazetteer Files page.