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, while the Sacramento metropolitan area with 2.46 million residents is the 27th-largest metropolitan area in the nation.

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.

Sacramento is the seat of the California Legislature and the governor of California. It is a major center for the California healthcare industry, as the seat of Sutter Health, UC Davis Medical Center, and the UC Davis School of Medicine. In 2013, the Sacramento Convention and Visitors Bureau stated that the city receives 15.3 million visitors per year, and is home to the California Museum, Crocker Art Museum, California State Railroad Museum, California State Capitol Museum, the Sacramento Convention Center Complex, and Old Sacramento State Historic Park.

Nisenan (Southern Maidu), Modoc, and Plains Miwok American Indians have lived in the area for perhaps thousands of years. Until the settlers arrived who would eventually make Sacramento their home, these tribes left little evidence of their existence. Their diet was dominated by acorns taken from the plentiful oak trees in the region and by fruits, bulbs, seeds, and roots gathered throughout the year.

In 1808, the Spanish explorer Gabriel Moraga encountered and named the Sacramento Valley and the Sacramento River. A Spanish writer with the Moraga expedition wrote:

Canopies of oaks and cottonwoods, many festooned with grapevines, overhung both sides of the blue current. Birds chattered in the trees and big fish darted through the pellucid depths. The air was like champagne, and (the Spaniards) drank deep of it, drank in the beauty around them. "¡Es como el sagrado sacramento! (It's like the Blessed Sacrament.)"

The valley and the river were then christened after the "Most Holy Sacrament of the Body and Blood of Christ," referring to the Catholic sacrament of the Eucharist.

John Sutter Sr. first arrived in the area on August 13, 1839, at the confluence of the American and Sacramento Rivers with a Mexican land grant of 50,000 acres (20,000 ha). The next year, he and his party established Sutter's Fort, a massive adobe structure with walls 18 feet (5.5 m) high and three feet (0.91 m) thick.