A rare forest inventory conducted in 1930s California has been digitized for the ~ 650 km-long Sierra Nevada Mountains. The survey mapped the dominant vegetation and surveyed some 7200 vegetation plots. We compare the historical extent of vegetation types by comparing the historical vegetation GIS with a 1996 measure of landcover. We compare the historical plot data with contemporary plots to develop a sense of how forest structure has changed over that time. Ponderosa Pine-dominated forests have been greatly reduced, and oak-dominated woodlands have expanded. These measured historical trends are consistent with predicted trends in vegetation for the region under future climate change. We examine the difference in change on lands managed in different ways.