 State Route 20 | ||||
|---|---|---|---|---|
 SR 20 highlighted in red | ||||
| Route information | ||||
| Maintained byCaltrans | ||||
| Length | 211.882 mi[1] (340.991 km) (plus about 15.5 mi (25 km) onUS 101) | |||
| History | State highway in 1910–1919; numbered in 1934 | |||
| Tourist routes |   Yuba-Donner Scenic Byway | |||
| Restrictions | No hazardous material along the northeast shore ofClear Lake betweenSR 29 andSR 53[2] | |||
| Major junctions | ||||
| West end |  SR 1 inFort Bragg | |||
| Major intersections | ||||
| East end |  I-80 nearEmigrant Gap | |||
| Location | ||||
| Country | United States | |||
| State | California | |||
| Counties | Mendocino,Lake,Colusa,Sutter,Yuba,Nevada,Placer | |||
| Highway system | ||||
| ||||
State Route 20 (SR 20) is astate highway in the northern-central region of the U.S. state ofCalifornia, running east–west north ofSacramento from theNorth Coast to theSierra Nevada. Its west end is atSR 1 inFort Bragg, from where it heads east pastClear Lake,Colusa,Yuba City,Marysville andNevada City toI-80 nearEmigrant Gap, where eastbound traffic can continue on other routes toLake Tahoe orNevada.
Portions of SR 20 are built near the routing of what was first awagon road and later aturnpike in the late 19th century. This road was extended through the state highway system all the way toUkiah in the early 20th century, and the missing link nearClear 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 theGrass Valley portion of the route tofreeway standards.
State Route 20 begins atSR 1 in southernFort Bragg, less than 1 mile (1.6 km) from the Pacific Ocean. It heads east, quickly climbing into theMendocino Range along a ridge and crossing throughDunlap Pass. The highway continues to rise alongside theNorth Fork Big River and tributaries, crossing another summit and then descending toWillits in theLittle Lake Valley viaBroaddus Creek. Anoverlap withUS 101 begins in Willits and heads southeasterly toCalpella, north ofUkiah inRedwood Valley. There SR 20 turns east again, crossing theRussian River, passing the north shore ofLake Mendocino, and rising to a summit via theEast Fork Russian River andCold Creek. The roadway again descends alongside theBlue Lakes andScotts Creek to the junction withSR 29 and the settlement ofUpper Lake in theClear Lake Basin. SR 20 closely follows the northeast shore of Clear Lake, staying right above the water line to avoid the adjacent hills. Where the lake ends, SR 20 continues east, intersectingSR 53 and then following theNorth Fork Cache Creek and tributaries to theLake–Colusa county line. During its final descent into theSacramento Valley, SR 20 intersectsSR 16 and curves north and back east, entering the valley viaSalt Creek.[3]
Once it enters the flat Sacramento Valley, SR 20 takes a generally straight path, crossingI-5 inWilliams, overlappingSR 45 near the west bank of theSacramento River southeast fromColusa, and then turning back east to cross the Sacramento River andSutter Bypass on its way toYuba City. The route crossesSR 99 west of central Yuba City, and runs east through northern Yuba City to theFeather River, which it crosses on the10th Street Bridge intoMarysville. Within the central part of that city, SR 20 makes several turns, first turning south from 10th Street onto E Street, then east on 9th Street (overlappingSR 70), north on B Street, and east on 12th Street (splitting from SR 70). The highway leaves Marysville to the northeast, paralleling theYuba River on its north side as it enters the foothills of theSierra Nevada.[3]
SR 20 rises into the Sierra along the north side of the Yuba River, crossing to the south side nearSmartsville and then climbing through several ravines to thePenn Valley. The current alignment, built in the mid-1980s as a mostlytwo-lane freeway, continues east across rugged terrain to the city ofGrass Valley, where it joinsSR 49 on the Golden Center Freeway. The two routes travel northeast toNevada City, where SR 49 turns northwest and SR 20 resumes its eastward course as a two-lane highway. The roadway climbs from Nevada City and follows Harmony Ridge and Washington Ridge before descending into theBear Valley via a series ofhairpin turns, and then climbing, just north ofEmigrant Gap, to its end atI-80 atYuba Pass.[3] The Pioneer Trail, aNational Recreation Trail, parallels SR 20 from a point on Harmony Ridge to the Bear Valley, and includes parts of a branch of theCalifornia Trail first used in 1850.[4]
SR 20 east of US 101 is part of theCalifornia Freeway and Expressway System,[5] although it is mostly a two-lane surface road; west of SR 29 and east of SR 53, it is part of theNational Highway System,[6] a network of highways that are considered essential to the country's economy, defense, and mobility by theFederal Highway Administration.[7] All of SR 20 is on theInterregional Road System, a highway system that connects major economic centers of the state,[8] and has been selected by theCalifornia Department of Transportation (Caltrans) as a High Emphasis Route and Focus Route from US 101 toSR 29 andSR 53 to I-80, with the designated corridor following SR 29 and SR 53 around the south side of Clear Lake.[9][10] It is also eligible for theState Scenic Highway System from SR 1 toSR 16 andSR 49 to I-80,[11] and has been designated as such for 6 miles (9.7 km) near the east end;[12] this is part of the federally designatedYuba-Donner Scenic Byway, aNational Forest Scenic Byway that uses SR 20 east of SR 49.[13]
The east end of SR 20, from Bear Valley (just below Emigrant Gap) to Nevada City, closely follows a branch of theTruckee Route of the California Trail, first used by California-bound emigrants in 1850.[4] Later a turnpike was built here by the same company that opened thePacific Turnpike (Culbertson Road and Bowman Lake Road betweenDutch Flat andBowman Lake) in 1864.[14]
By the end of the 1910s, a passabledirt andgravel road connected Ukiah and Nevada City via the south side ofClear Lake and Marysville. The portion betweenLower Lake andWilbur Springs was impassable in wet weather, at which times theBartlett Springs and Bear Valley Toll-road via Upper Lake andBartlett 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 andRough and Ready (where it used Spenceville Road). Beyond Nevada City to Emigrant Gap, the old turnpike was not passable; instead the presentSR 174 was available for eastward drivers. Between Williams and Colusa, the road was paved inconcrete,[15][16] 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 thecounty seat of Colusa.[17]
This state highway was significantly extended in both directions in 1919, west to Ukiah and east to Emigrant Gap,[17] creating what was known as the Tahoe-Ukiah Highway, connecting Ukiah andLake Tahoe in combination withRoute 37 (now I-80) andRoute 38 (nowSR 89).[18] The law that defined the extension simply stated that it would connect "Ukiah to Tahoe City";[19] the state decided in September 1925 that it would run the highway along the north shore of Clear Lake, combining with the plannedRumsey-Lower Lake Highway (Route 50, now SR 53 and SR 16) east to Wilbur Springs.[20][21] With the completion of this segment in mid-1932, the highway was ready for heavy travel,[22] and became Sign Route 20 in 1934 as part of the initial signed state route system.[23]
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.[24] This was constructed (over an existingcounty road[25]) and became part of Sign Route 20 prior to 1964,[26] when the Route 20 designation was legislatively adopted.[27] 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.[28]
Except where prefixed with a letter,postmiles were measured on the road as it was in1964, based on the alignment that existed at the time, and do not necessarily reflect current mileage. R reflects a realignment in the route since then, M indicates a second realignment, L refers to an overlap due to a correction or change, and T indicates postmiles classified as temporary (for a full list of prefixes, seeCalifornia postmile § Official postmile definitions).[1] Segments that remain unconstructed or have been relinquished to local control may be omitted. The numbers reset at county lines; the start and end postmiles in each county are given in the county column.
| County | Location | Postmile [1][28][29] | Exit [30][31] | Destinations | Notes |
|---|---|---|---|---|---|
| Mendocino MEN R0.00-44.11 | Fort Bragg | R0.00 | SR 1 (Shoreline Highway) –Caspar,Fort Bragg | Western terminus | |
| | 33.217 |   US 101 north –Eureka | West end of US 101 overlap; US 101 exit 568 | ||
| West end of freeway on US 101 | |||||
| | R32.63[N 1] | 557 | West Road –Redwood Valley | Exit number follows US 101 | |
| | | East end of freeway on US 101 | |||
| | 41.06[N 1][32] | Ridgewood Summit | |||
| | | West end of freeway on US 101 | |||
| Calpella | 30.83[N 1] 33.22 | East end of freeway on US 101 | |||
 US 101 south –Ukiah | Trumpet interchange; east end of US 101 overlap; US 101 exit 555B | ||||
| | 33.77 | Road 230 –Redwood Valley | Interchange via connector road; servesRedwood Valley Rancheria | ||
| Lake LAK 0.00-46.48 | Upper Lake | 8.32 |    SR 29 south –Lakeport,Kelseyville | Roundabout; northern terminus of SR 29; servesSutter Lakeside Hospital | |
| | 31.62 |  SR 53 –City of Clearlake,Lower Lake,Lakeport | Roundabout; northern terminus of SR 53 | ||
| Colusa COL 0.00-R39.34 | Wilbur Springs | 3.45 |   SR 16 east –Woodland | Western terminus of SR 16 | |
| Williams | T20.56 |   SR 20 Bus. east (E Street) | |||
| R21.85 | Williams (I-5 BL) | Interchange via connector road; formerUS 99W | |||
| R22.12 |  I-5 –Redding,Sacramento | Interchange; I-5 exit 578 | |||
| T23.19 |  SR 20 Bus. west (Husted Road) / Freshwater Road | ||||
| Colusa | 31.09 |   SR 45 north (Market Street west) –Princeton | West end of SR 45 overlap | ||
| | 36.79 | SR 45 south / Steidlmayer Road –Grimes | East end of SR 45 overlap | ||
| Sacramento River | 39.34 0.00 | Meridian Bridge | |||
| Sutter SUT R0.00-17.06 | Yuba City | 15.57 |  SR 99 –Chico,Sacramento | ||
| 16.84 | Sutter Street / 2nd Street | Interchange; 2nd Street not signed westbound | |||
| Feather River | 17.06 0.00 | 10th Street Bridge | |||
| Yuba YUB 0.00-21.67 | Marysville | 0.57 | I Street | Right-in/right-out interchange; eastbound exit and entrance | |
| 0.99 |  SR 70 south (E Street south) –Sacramento | West end of SR 70 overlap; formerUS 99E south | |||
| 1.47 | SR 70 north (B Street north) –Oroville | East end of SR 70 overlap | |||
| | 13.27 |  CR E21 (Marysville Road) –Browns Valley,Dobbins,Brownsville | Southern terminus of CR E21; servesCollins Lake,Bullards Bar Reservoir | ||
| Nevada NEV 0.00-41.287 | | 6.60 | Rough and Ready Highway / Penn Valley Drive –Rough and Ready,Penn Valley | At-grade intersection; west end of Eric W. Rood Memorial Expressway | |
| Grass Valley | R12.16 | — | McCourtney Road / Mill Street | Interchange; McCourtney Road not signed westbound | |
| R12.24 | East end of Eric W. Rood Memorial Expressway | ||||
| R12.24– R12.30 |  SR 49 south / Empire Street east –Auburn | Interchange; west end of SR 49 overlap | |||
| R12.30 | West end of freeway | ||||
| R12.92 | 182A |  SR 174 –Colfax,Grass Valley | Northern terminus of SR 174 | ||
| R13.61 | 182B | Idaho Maryland Road | Eastbound signage | ||
| E. Main Street | Westbound signage | ||||
| R14.27 | 183A | Dorsey Drive | |||
| R14.80 | 183B | Brunswick Road | |||
| Nevada City | R15.92 | 185A | Gold Flat Road / Ridge Road | Signed as exit 185 westbound | |
| R16.74 | 185B | Sacramento Street –Nevada City | Eastbound exit and westbound entrance | ||
| R16.99 | 186 | Broad Street | Eastbound exit and westbound entrance | ||
| R17.24 | Coyote Street –Historical District | No eastbound exit | |||
| East end of freeway | |||||
| R17.40 | SR 49 north / Uren Street –Downieville | East end of SR 49 overlap | |||
| Placer PLA 41.287-43.87 | Bear River | 41.29 | Bridge | ||
| Nevada NEV 43.87-45.66 | | 45.66 | I-80 –Reno,Sacramento | Interchange; eastern terminus; I-80 exit 161 | |
1.000 mi = 1.609 km; 1.000 km = 0.621 mi
| |||||
 State Route 20 Business | |
|---|---|
| Location | Williams, California |
State Route 20 Business (SR 20 Bus.) is abusiness route of California State Route 20 inWilliams. It provides access to downtown Williams asE Street andHusted Road. The business route follows the original routing of SR 20 from its western terminus toInterstate 5. East of I-5, the original routing, which headed northeast out of Williams, has since been abandoned. The present-day route continues on E Street east to Husted Road, then turns north to the business route's eastern terminus at SR 20 at the northeastern tip of Williams.
The entire route is inWilliams,Colusa County.
| mi | km | Destinations | Notes | ||
|---|---|---|---|---|---|
| 0.0 | 0.0 | SR 20 –Clear Lake,Colusa | Western terminus | ||
| Module:Jctint/USA warning: Unused argument(s): state | |||||
| 1.3 | 2.1 |  I-5 BL (7th Street) | FormerUS 99W | ||
| 1.7 | 2.7 | I-5 –Sacramento,Redding | Interchange; I-5 exit 577 | ||
| 2.3 | 3.7 | Husted Road south | |||
| 3.3 | 5.3 | SR 20 | Eastern terminus | ||
| 3.3 | 5.3 | Freshwater Road | Continuation beyond SR 20 | ||
| 1.000 mi = 1.609 km; 1.000 km = 0.621 mi | |||||
