Plumas County is a county located in the Sierra Nevada of the U.S. state of California. As of the 2020 census, the population was 19,790. The county seat is Quincy, and the only incorporated city is Portola. The largest community in the county is East Quincy. The county was named for the Spanish Río de las Plumas, which flows through it. The county itself is also the namesake of a native moth species, Hadena plumasata.
State Route 99 (SR 99) is a north–south state highway in the U.S. state of California, stretching almost the entire length of the Central Valley. From its southern end at Interstate 5 (I-5) near Wheeler Ridge to its northern end at SR 36 near Red Bluff, SR 99 goes through the densely populated eastern parts of the valley. Cities served include Bakersfield, Delano, Tulare, Visalia, Fresno, Madera, Merced, Turlock, Modesto, Manteca, Stockton, Sacramento, Yuba City, and Chico.
State Route 24 is a heavily traveled east–west state highway in the U.S. state of California that serves the eastern side of the San Francisco Bay Area. A freeway throughout its entire length, it runs from the Interstate 580/Interstate 980 interchange in Oakland, and through the Caldecott Tunnel under the Berkeley Hills, to the Interstate 680 junction in Walnut Creek. It lies in Alameda County, where it is highly urban, and Contra Costa County, where it passes through wooded hillsides and suburbs. SR 24 is a major connection between the San Francisco–Oakland Bay Bridge/MacArthur Maze complex and the inland cities of the East Bay.
State Route 160 is a state highway in the U.S. state of California consisting of two sections. The longer, southern, section is a scenic highway through the alluvial plain of the Sacramento River, linking SR 4 in Antioch with Sacramento via the Antioch Bridge. The northern section, separated from the southern by Sacramento city streets, is the North Sacramento Freeway, running from the 16th Street Bridge over the American River to Interstate 80 Business towards Roseville.
State Route 126 is a state highway in the U.S. state of California that serves Ventura and Los Angeles counties. The route runs from U.S. Route 101 in Ventura to Interstate 5 at the Castaic Junction-Santa Clarita border through the Santa Clara River Valley. The highway is an important connector highway in Ventura County, and serves as an alternate route into the Santa Clarita Valley, and the San Fernando Valley area of Los Angeles and the High Desert of Antelope Valley.
State Route 12 is a state highway in the U.S. state of California that travels in an east–west direction from State Route 116 in Sebastopol in Sonoma County to State Route 49 just north of San Andreas in Calaveras County. The route connects the Sonoma and Napa valleys with the Sacramento–San Joaquin River Delta and the Sierra Foothills. It is constructed to freeway standards from the Fulton Road/South Wright Road stoplight in Santa Rosa, to its partial interchange with Farmers Lane.
State Route 4 is a state highway in the U.S. state of California, routed from Interstate 80 in the San Francisco Bay Area to State Route 89 in the Sierra Nevada. It roughly parallels the Sacramento-San Joaquin River Delta, a popular area for boating and fishing, with a number of accesses to marinas and other attractions. After crossing the Central Valley, the highway ascends up the Sierra foothills. It passes through Ebbetts Pass and contains the Ebbetts Pass Scenic Byway, a National Scenic Byway.
State Route 68 is a state highway in the U.S. state of California, located entirely in Monterey County. It runs from Asilomar State Beach in Pacific Grove to U.S. Route 101 in Salinas. The approximately 20-mile (32 km) long highway serves as a major route between the Monterey Peninsula and Salinas.
State Route 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.
State Route 29 is a state highway in the U.S. state of California that travels from Interstate 80 in Vallejo north to State Route 20 in Upper Lake. It serves as the primary road through the Napa Valley, providing access to the Lake County region to the north and the rest of the San Francisco Bay Area to the south.
State Route 89 is a state highway in the U.S. state of California that travels in the north–south direction, serving as a major thoroughfare for many mountain communities in the Sierra Nevada and the Cascade Range. It starts from U.S. Route 395 near Topaz Lake, winding its way up to the 8,314-foot (2,534 m) Monitor Pass, down to the Carson River, and up again over the 7,740-foot (2,359 m) Luther Pass. From that point on, the route generally loses elevation on its way past Lake Tahoe, through Tahoe and Plumas National Forests until Lake Almanor. For roughly nine miles the route is then a part of State Route 36. The route then ascends to the 5,753-foot (1,754 m) Morgan Summit. After it enters Lassen Volcanic National Park it continues to gain elevation until it reaches its highest point in an unnamed pass in the middle of Lassen Peak and Bumpass Mountain. The road then descends and heads northwest, finally terminating at Interstate 5 at the foot of Mount Shasta at around 3,600 feet (1,100 m).
State Route 36 is an east–west state highway in the U.S. state of California that is routed from U.S. Route 101 in Humboldt County to U.S. Route 395 just east of Susanville in Lassen County. The highway passes through Red Bluff, the county seat of Tehama County, on the northern edge of the Sacramento Valley. The portion of SR 36 travelling past Lassen Volcanic National Park and Lake Almanor is part of the Volcanic Legacy Scenic Byway, a National Scenic Byway. Also, Route 36 between Alton and Susanville is a designated Blue Star Memorial Highway.
State Route 198 is an east–west state highway in the U.S. state of California that runs from U.S. Route 101 south of King City to Sequoia National Park. It connects the California Central Coast to the mid–Central Valley through Hanford and Visalia, although the most developed portion is in the Central Valley itself. SR 198 intersects the major north–south routes in the Central Valley, including Interstate 5 (I-5), SR 33, and SR 99.
State Route 65 is a north-south state highway in the U.S. state of California. It is composed of two segments in the Central Valley. The southern segment begins at SR 99, near Bakersfield and terminates at SR 198 near Exeter. It also serves the communities of Oildale, Ducor, Terra Bella, Porterville, Strathmore, and Lindsay. The northern segment begins at Interstate 80 in Roseville and terminates at SR 70 at Olivehurst. It also serves the communities of Rocklin, Lincoln, and Wheatland.
State Route 180 is a state highway in the U.S. state of California. It runs through the heart of the San Joaquin Valley from State Route 33 in Mendota through Fresno, and then east towards the Sierra Nevada to Kings Canyon National Park.
Beckwourth Pass is the lowest mountain pass in the Sierra Nevada mountain range at an elevation of 5,221 feet (1,591 m).
State Route 162 is a state highway in the U.S. state of California that runs roughly west–east through the Coast Ranges and the Sacramento Valley to the western slopes of the Sierra Nevada. It begins at U.S. Route 101 near Longvale, in Mendocino County, and ends at Brush Creek, in Butte County. For most of its length, it is a two lane, undivided highway. SR 162 is not signed as a contiguous route through Mendocino National Forest in Mendocino and Glenn counties. Instead, the portion inside the national forest is federally maintained by the U.S. Forest Service as Forest Highway 7 (FH 7), and is not included in the state route logs.
State Route 149 is a short state highway in the U.S. state of California that helps to connect Oroville and Chico through rural Butte County. Connecting State Route 70 at Wicks Corner with State Route 99 east of Durham, it forms part of the primary north–south highway through the eastern Sacramento Valley, a Focus Route of the Interregional Road System.
U.S. Route 50 (US 50) is a transcontinental United States Numbered Highway, stretching from West Sacramento, California, in the west to Ocean City, Maryland, in the east. The California portion of US 50 runs east from Interstate 80 (I-80) in West Sacramento to the Nevada state line in South Lake Tahoe. A portion in Sacramento also has the unsigned designation of Interstate 305. The western half of the highway in California is a four-or-more-lane divided highway, mostly built to freeway standards, and known as the El Dorado Freeway outside of downtown Sacramento. US 50 continues as an undivided highway with one eastbound lane and two westbound lanes until the route reaches the canyon of the South Fork American River at Riverton. The remainder of the highway, which climbs along and out of the canyon, then over the Sierra Nevada at Echo Summit and into the Lake Tahoe Basin, is primarily a two-lane road.
Interstate 5 (I-5) is a major north–south route of the Interstate Highway System in the United States, stretching from the Mexican border at the San Ysidro crossing to the Canadian border near Blaine, Washington. The segment of I-5 in California runs 796.77 miles (1,282.28 km) across the length of the state from San Ysidro to the Oregon state line south of the Medford-Ashland metropolitan area. It is the longest interstate in California, and accounts for more than half of I-5's total length. It is also the second longest stretch of Interstate Highway with a single designation within a single state after I-10 in Texas.
Feather River Scenic Byway
SR 99 near Pleasant Grove 
US 395 at Hallelujah Junction 
