The 20th Century was a period of enormous change for western forests. Fire used to maintain distinct forest vegetation communities – pine, dry mixed-conifer, mesic mixed-conifer, and spruce-fir – in close proximity to one another along steep vertical gradients in the topographically diverse forests of the American Southwest. How did these forests change in response to fire exclusion? In what ways and how rapidly? What are the consequences of these changes? It is important to provide context for the condition of today’s forests, but more importantly, how can this information help today’s managers?