The Earth Surface Dynamics section of the USGS provides this excellent collection of graphics, depicting range maps for more than 100 common North American tree species. From Abies amabilis to Yucca brevifolia, these color maps may be viewed or downloaded (.pdf, .zip, tgz). Most of the ranges depicted here were digitized by Elbert L. Little, Jr. (USDA Forest Service) for vegetation-climate modeling studies; graphics are best viewed as downloaded files.