Sacramento Valley in the context of "U.S. Route 40 in California"

Interstate 80 (I-80) is a transcontinental Interstate Highway in the United States, stretching from San Francisco, California, to Teaneck, New Jersey. The segment of I-80 in California runs east from San Francisco across the San Francisco–Oakland Bay Bridge to Oakland, where it turns north and crosses the Carquinez Bridge before turning back northeast through the Sacramento Valley. I-80 then traverses the Sierra Nevada, cresting at Donner Summit, before crossing into the state of Nevada within the Truckee River Canyon. The speed limit is at most 65 mph (105 km/h) along the entire route instead of the state's maximum of 70 mph (110 km/h) as most of the route is in either urban areas or mountainous terrain. I-80 has portions designated as the Eastshore Freeway and Alan S. Hart Freeway.

Throughout California, I-80 was built along the corridor of US Route 40 (US 40), eventually replacing this designation entirely. The prior US 40 corridor itself was built along several historic corridors in California, notably the California Trail and Lincoln Highway. The route has changed from the original plans in San Francisco due to freeway revolts canceling segments of the originally planned alignment. Similarly in Sacramento, the freeway was rerouted around the city after plans to upgrade the original grandfathered route through the city to Interstate Highway standards were canceled.

Sacramento is the capital city of the U.S. state of California. The county seat of Sacramento County, it is located at the confluence of the Sacramento and American Rivers in the Sacramento Valley. It is the fourth-most populous city in Northern California, sixth-most populous city in the state, and 35th-most populous city in the United States, with a population of 524,943 at the 2020 census. The Sacramento metropolitan area, with 2.46 million residents, is the 27th-largest metropolitan area in the country.

Before the arrival of the Spanish, the area was inhabited by the Nisenan, Maidu, and other indigenous peoples of California. In 1808, Spanish cavalryman Gabriel Moraga surveyed and named the Río del Santísimo Sacramento (Most Holy Sacrament River), after the Blessed Sacrament. In 1839, Juan Bautista Alvarado, Mexican governor of Alta California, granted the responsibility of colonizing the Sacramento Valley to Swiss-born Mexican citizen John Augustus Sutter, who subsequently established Sutter's Fort and the settlement at the Rancho Nueva Helvetia. Following the American Conquest of California and the 1848 Treaty of Guadalupe-Hidalgo, the waterfront developed by Sutter began to be developed and incorporated in 1850 as the City of Sacramento. In 1852, the city offered its county courthouse to the state of California to house the state legislature, resulting in the city becoming the permanent state capital in 1854 and ushering in the construction of a new state capitol building which was finished in 1874.

Chico (/ˈtʃiːkoʊ/ CHEE-koh; Spanish for "little boy") is the most populous city in Butte County, California, United States. Located in the Sacramento Valley region of Northern California, the city had a population of 101,475 in the 2020 census, an increase from 86,187 in the 2010 census. Chico is the cultural and economic center of the northern Sacramento Valley, as well as the most populous city in California north of the capital city of Sacramento. The city is known as a college town, as the home of California State University, Chico, and for Bidwell Park, one of the largest urban parks in the world.

Davis is the most populous city in Yolo County, California, United States. Located in the Sacramento Valley region of Northern California, the city had a population of 66,850 in 2020, not including the on-campus population of the University of California, Davis, which was over 9,400 (not including students' families) in 2016. As of 2023, there were 40,850 students enrolled at the university, and is known as the biking capital of America.

Roseville is the most populous city in Placer County, California, located within the Sacramento metropolitan area. At the 2020 census, the city's population was 147,773, making it the third-largest city in the Sacramento area. Interstate 80 runs through Roseville and State Route 65 runs through part of the northern edge of the city.

Historically associated with the railroad, the city underwent significant urban renewal in the 1980s and 1990s. Today it has become a major commercial hub, attracting regular shoppers and visitors from a large swath of rural southeastern Sacramento Valley and the Sierra Nevada foothills. In recent years, it has seen significant population growth and new single-family home developments, becoming a "boomburb" or edge city of Sacramento.

Mendocino County (/ˌmɛndəˈsiːnoʊ/ ; Mendocino, Spanish for "of Mendoza") is a county located on the North Coast of the U.S. state of California. As of the 2020 United States census, the population was 91,601. The county seat is Ukiah.

Mendocino County consists wholly of the Ukiah, California Micropolitan Statistical Area (μSA) for the purposes of the U.S. Census Bureau. It is located approximately equidistant from the San Francisco Bay Area and California/Oregon border, separated from the Sacramento Valley to the east by the California Coast Ranges. While smaller areas of redwood forest are found farther south, it is the southernmost California county to be included in the World Wildlife Fund's Pacific temperate rainforests ecoregion, the largest temperate rainforest ecoregion on Earth.

The Sacramento River (Spanish: Río Sacramento) is the principal river of Northern California in the United States and is the largest river in California. Rising in the Klamath Mountains, the river flows south for 400 miles (640 km) before reaching the Sacramento–San Joaquin River Delta and San Francisco Bay. The river drains about 26,500 square miles (69,000 km) in 19 California counties, mostly within the fertile agricultural region bounded by the Coast Ranges and Sierra Nevada known as the Sacramento Valley, but also extending as far as the volcanic plateaus of Northeastern California. Historically, its watershed has reached as far north as south-central Oregon where the now, primarily, endorheic (closed) Goose Lake rarely experiences southerly outflow into the Pit River, the most northerly tributary of the Sacramento.

The Sacramento and its wide natural floodplain were once abundant in fish and other aquatic creatures, notably one of the southernmost large runs of chinook salmon in North America. For about 12,000 years, humans have depended on the vast natural resources of the watershed, which had one of the densest Native American populations in California. The river has provided a route for trade and travel since ancient times. Hundreds of tribes sharing regional customs and traditions have inhabited the Sacramento Valley, first coming into contact with European explorers in the late 1700s. The Spanish explorer Gabriel Moraga named the river Rio de los Sacramentos in 1808, later shortened and anglicized into Sacramento.

Placer County (/ˈplæsər/ PLASS-ər), officially the County of Placer, is located in the U.S. state of California. As of the 2020 United States census, the population was 404,739. The county seat is Auburn.

Placer County is included in the Greater Sacramento metropolitan area. It is in both the Sacramento Valley and Sierra Nevada regions, in what is known as the Gold Country. The county stretches roughly 65 miles (105 km) from Sacramento's suburbs at Roseville to the Nevada border and the shore of Lake Tahoe.