Range map of <i><b><a href="//commons.wikimedia.org/wiki/Category:Alnus_rubra" title="Category:Alnus rubra">Alnus rubra</a></b></i>.
U.S. Geological Survey
Digital representation of "Atlas of United States Trees" by Elbert L. Little, Jr. <a rel="nofollow" class="external autonumber" href="https://esp.cr.usgs.gov/data/atlas/little/">[1]</a>