California State Route 20

State Route 20 (SR 20) is a state highway in the northern-central region of the U.S. state of California, running east–west north of Sacramento from the North Coast to the Sierra Nevada. Its west end is at SR 1 in Fort Bragg, from where it heads east past Clear Lake, Colusa, Yuba City, Marysville and Nevada City to I-80 near Emigrant Gap, where eastbound traffic can continue on other routes to Lake Tahoe or Nevada.

Portions of SR 20 are built near the routing of what was first a wagon road and later a turnpike in the late 19th century. This road was extended through the state highway system all the way to Ukiah in the early 20th century, and the missing link near Clear Lake was completed in 1932 before the official designation of this highway as SR 20 in 1934. There have been subsequent improvements to the road, such as the conversion of the Grass Valley portion of the route to freeway standards.

Route description

Route 20 is defined in section 320 of the California Streets and Highways Code. The definition omits the concurrency with Route 101 instead of duplicating that segment in the other route's definition in the code:

Route 20 is from:

(a) Route 1 near Fort Bragg to Route 101 at Willits.

(b) Route 101 to Route 80 near Emigrant Gap via Williams and Colusa.

State Route 20 begins at SR 1 in southern Fort Bragg, less than 1 mile (1.6 km) from the Pacific Ocean. It heads east, quickly climbing into the Mendocino Range along a ridge and crossing through Dunlap Pass.