PAD-US (Protected Areas Database of the United States)

PAD-US is the official national inventory of US land and marine areas set aside for biodiversity, recreation or cultural use and managed for those purposes through legal or other effective means.¹ It is maintained by the Gap Analysis Project of the US Geological Survey.¹ Federal agencies supply their own boundaries through the Federal Geographic Data Committee's Federal Lands Working Group, and state, local and nonprofit data stewards add theirs.^1,3 It holds all federal land and most state and local land, mostly parcels owned outright by agencies and nonprofits, plus conservation easements that can be published.¹ Private conservation land is included only where it was voluntarily provided.¹

Each parcel records its owner, its manager, its designation (a wilderness area, a national forest, a state park), its name, its size and whether the public can get in for recreation.¹ It also carries a GAP Status Code, a measure of how firmly the land is meant to stay natural:¹

• 1: permanent protection with natural disturbance left to run, as in wilderness areas and several national parks¹
• 2: permanent protection with some uses that degrade natural communities, as in national wildlife refuges¹
• 3: protection from conversion over most of the area, with logging, mining or off-road vehicles allowed, as in national forests and BLM land¹
• 4: no known mandate or easement against conversion, as in private, developed or farmed land¹

An IUCN category and a World Database on Protected Areas site code link each record to the global inventory behind Protected Planet.^1,3

For a model of a place, PAD-US says who owns and manages the open land and how strongly it is protected.¹ Across agency lines it is the public-land part of the rules layer. The overview lists uses from biodiversity planning and climate corridors to siting energy projects and planning parks.¹ It is a compilation, so for one agency's land, for data that changes often, or for any use with a regulatory outcome, the authoritative agency data and field surveys should be checked.¹ Comparing two versions to find changes in protection is discouraged, since many differences come from better agency GIS rather than land changing hands.²

The current version, 4.1, came out in March 2025, almost sixteen years after version 1.0 in April 2009.³ The national download is one geodatabase holding the fee, designation, easement, proclamation and marine layers, with overlaps.² State and territory downloads come as geodatabases and KMZ files, and separate vector and raster analysis files remove overlaps by GAP status.² Web services, a statistics dashboard and the processing scripts are also published.^1,2 The data release is in the public domain and is cited through the DOI 10.5066/P96WBCHS.^1,4