California State Route 20

State Route 20
SR 20 highlighted in red
Route information
Maintained by Caltrans
Length	211.882 mi[1] (340.991 km) (plus about 15.5 mi (25 km) on US 101)
History	State highway in 1910–1919; numbered in 1934
Tourist routes	Yuba-Donner Scenic Byway
Restrictions	No hazardous material along the northeast shore of Clear Lake between SR 29 and SR 53[2]
Major junctions
West end	SR 1 in Fort Bragg
Major intersections	US 101 from Willits to Calpella SR 29 near Upper Lake SR 53 near Clearlake I-5 in Williams SR 99 in Yuba City SR 49 from Grass Valley to Nevada City
East end	I-80 near Emigrant Gap
Location
Country	United States
State	California
Counties	Mendocino, Lake, Colusa, Sutter, Yuba, Nevada, Placer
Highway system
State highways in California Interstate US State Scenic History Pre‑1964 Unconstructed Deleted Freeways
← SR 19 → SR 22

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.