The Urban Dictionary says:

- Redwood Curtain (adj) The Redwood Curtain (RC) is the extreme northwestern corner of California, i.e. the coastal counties of Del Norte, Humboldt and Mendocino. The RC is the northern Californian version of the Iron Curtain in eastern Europe erected during the Cold War and is mostly used in a derogatory sense, whereby the RC symbolizes the area’s lack of cultural or metropolitan qualities as well as poor transportation access, sparse development, rugged geography, and a strong provincialism among the native locals. -

Years ago, breaching the Redwood Curtain meant negotiating Highway 101 as it dwindled to a potholed, two-lane road that twisted in and out of river canyons and slalomed around individual redwood trees.

But ‘Caltrans’ has been busy over the intervening quarter-century, straightening the worst of the curves and transforming the road, for the most part, into a modern, four-lane highway. It’s shaved close to an hour off the drive and untold wear from drivers’ nerves.

Still, the notion of the Redwood Curtain persists and Humboldt County remains a place apart; separated by landscape and culture, if not distance, from the rest of California.