Information sources provided by the U.S. government, or one of its agencies, will have website addresses (URLs) that end in .gov (e.g. www.xyz.gov)

GovInfo – A service of the U.S. Government Publishing Office (GPO), GovInfo provides free online access to official publications from all three branches of the federal government, including the Federal Register, Code of Federal Regulations (CFR), and other regulatory documents.

Bureau of Land Management (BLM) 
The BLM website offers data and maps related to federally managed lands, including recreational areas, mineral resources, and land use statistics. Their GIS data portal provides downloadable geospatial data.

U.S. Forest Service (USFS) - Forest Inventory and Analysis (FIA)
The USFS FIA program provides extensive data on forest conditions, land ownership, and ecological health for national forests and grasslands.