California State Route 20 - History

History

The east end of SR 20, from Bear Valley (just below Emigrant Gap) to Nevada City, closely follows a branch of the Truckee Route of the California Trail, first used by California-bound emigrants in 1850. Later a turnpike was built here by the same company that opened the Pacific Turnpike (Culbertson Road and Bowman Lake Road between Dutch Flat and Bowman Lake) in 1864.

By the end of the 1910s, a passable dirt and gravel road connected Ukiah and Nevada City via the south side of Clear Lake and Marysville. The portion between Lower Lake and Wilbur Springs was impassable in wet weather, at which times the Bartlett Springs and Bear Valley Toll-road via Upper Lake and Bartlett Springs was available for $1.50 each way or $2.50 round trip. This route generally followed the present SR 20, except around Clear Lake and between Marysville and Rough and Ready (where it used Spenceville Road). Beyond Nevada City to Emigrant Gap, the old turnpike was not passable; instead the present SR 174 was available for eastward drivers. Between Williams and Colusa, the road was paved in concrete, as it had been added to the state highway system as part of the first (1910) bond issue, specifically as Route 15, connecting the west Sacramento Valley trunk (Route 7, now I-5) with the county seat of Colusa.

This state highway was significantly extended in both directions in 1919, west to Ukiah and east to Emigrant Gap, creating what was known as the Tahoe-Ukiah Highway, connecting Ukiah and Lake Tahoe in combination with Route 37 (now I-80) and Route 38 (now SR 89). The law that defined the extension simply stated that it would connect "Ukiah to Tahoe City"; the state decided in September 1925 that it would run the highway along the north shore of Clear Lake, combining with the planned Rumsey-Lower Lake Highway (Route 50, now SR 53 and SR 16) east to Wilbur Springs. With the completion of this segment in mid-1932, the highway was ready for heavy travel, and became Sign Route 20 in 1934 as part of the initial signed state route system.

In 1953, the legislature added an extension of Route 15 from US 101 at Willits (north of Ukiah) west to SR 1 near Fort Bragg. This was constructed (over an existing county road) and became part of Sign Route 20 prior to 1964, when the Route 20 designation was legislatively adopted. Subsequent improvements include the construction of the Golden Center Freeway, connecting Grass Valley with Nevada City, in the late 1960s, and a new alignment of SR 20 west from Grass Valley, bypassing Rough and Ready, in the mid-1980s.