Three types of wild places are found among the lower 48 U.S. Protected Areas.
~650 Wilderness Areas – located in 42 of the lower 48 states – recognized by Congress. Wilderness Areas are parts of national parks, wildlife refuges, national forests, and BLM lands. These areas are afforded the highest level of protection for biodiversity conservation.
577 Wilderness Study Areas (WSAs)- primarily designated by BLM in western states.
Over 2600 Inventoried Roadless Areas (IRAs) identified by the Forest Service. Many IRAs (~500) are found outside of the western United States, but they are more often smaller areas under 10,000 acres.
Interactive map, use top left arrow to toggle to Human Footprint layer; then click back and Zoom in to view map. Zoom and click on any spot for score.
Human Footprint. Red areas are highest modification; dark blue areas are lowest (0 is lowest; 1 is highest score)
Over one-third of the 2500 Last Great Places are these wild lands, of which almost 400 are WSAs or IRAs.
The top places were assessed for conserving still unprotected wildland, using minimum thresholds and a weighted ranking of three key factors.
- Very low modification – score under .050 – 50%
- High landscape diversity – 75 or more land facets – 40%
- High Resilience – score over 1000 – 10%
The above are the top 10 ranked WSAs and IRAs with very low human modification, a very large variety of landscape features, and high resilience to climate change. The WSAs are now managed for biodiversity conservation.
Top-Ranked Wilderness Areas
| Wilderness in Top 20 Last Great Places | Ecoregion |
| John Muir Wilderness | Sierra Nevada |
| Gila Wilderness | AZ-NM Mountains |
| Absaroka-Beartooth Wilderness | Utah-Wyoming Mtns |
| Frank Church-River Of No Return Wilderness | Middle Rockies-Blue Mtns |
| Three Sisters Wilderness | West Cascades |
| Weminuche Wilderness | Southern Rockies |
| Mazatzal Wilderness | Apache Highlands |
| Ventana Wilderness | CA Central Coast |
| Bob Marshall Wilderness | Canadian Rockies |
| Glacier Peak Wilderness | North Cascades |
| West Elk Wilderness | Southern Rockies |