Description: Data Source: University of Montana Wilderness Institute (Wilderness.net); Modified by TWS to add URLs for Legislative History and Special Provisions databases. Data Vintage: May 2011. Data Limitations: Individual wilderness unit boundaries vary with respect to the scale at which they were prepared. Be aware that while many units can be appropriately viewed in the context of a national forest or BLM district, others may only be designed for reference in the context of roughly one-quarter of a typical western state's area.