The most variety: McKenzie Pass, Oregon
When to go: Mid-October; the highway closes in early November.
Why go: Driving from the Williamette Valley to the eastern slopes of the Cascades—Eugene to Sisters on Highway 242—presents a smorgasbord of landscapes. Transplants like the eastern black walnut and Norway maple in Eugene give the university town exotic color, while over the pass, the red of vine maples are juxtaposed with dark lava fields.
Where to get the best view: The Dee Wright Observatory is a striking little castle made of lava but its surrounding area is mostly treeless; the University of Oregon campus has plenty of orange and yellow specimens.
Insider tip: In downtown Eugene, look for deep red Dawn Redwoods, a rare deciduous conifer.