This paper develops techniques for the mapping of forest types in Arizona, New Mexico, and Wyoming. The methods involve regression-tree modeling using a variety of remote sensing and GIS layers along with Forest Inventory Analysis (FIA) point data. Regression-tree modeling is a fast and efficient technique of estimating variables for large data sets with high accuracy levels. If the methods developed in this paper are successful, they will be applied to the contiguous United States and Alaska producing a forest type map for these areas. This forest type map will update and improve an older version of the forest type map made in 1992.