Imperial County, California in the context of "San Diego–Imperial (California)"

Southern California (commonly shortened to SoCal) is a geographic and cultural region that generally comprises the southern portion of the U.S. state of California. Its densely populated coastal region includes Greater Los Angeles (the second-most populous urban agglomeration in the United States) and San Diego County (the second-most populous county in California). The region generally contains ten of California's 58 counties: Los Angeles, San Diego, Orange, Riverside, San Bernardino, Kern, Ventura, Santa Barbara, San Luis Obispo, and Imperial counties.

Although geographically smaller than Northern California in land area, Southern California has a higher population, with 23.76 million residents as of the 2020 census. The sparsely populated desert region of California occupies a significant portion of the area: the Colorado Desert, along with the Colorado River, is located on Southern California's eastern border with Arizona, and the Mojave Desert shares a border with Nevada to the northeast. Southern California's southern border with Baja California is part of the Mexico–United States border.

San Diego County (/ˌsæn diˈeɪɡoʊ/ ), officially the County of San Diego, is a county in the southwest corner of the U.S. state of California, north to its border with Mexico. As of the 2020 census, the population was 3,298,634; it is the second-most populous county in California and the fifth-most populous in the United States. Its county seat is San Diego, the second-most populous city in California and the eighth-most populous in the United States. It is the southwesternmost county in the 48 contiguous United States, and is a border county. It is home to 18 Indian reservations, the most of any county in the United States. There are 16 military installations of the U.S. Navy, Marine Corps, and Coast Guard in the county.

San Diego County comprises the San Diego–Chula Vista–Carlsbad, CA Metropolitan Statistical Area, which is the 18th most populous metropolitan statistical area and the 18th most populous primary statistical area in the United States. San Diego County is also part of the San Diego–Tijuana region, the largest metropolitan area shared between the United States and Mexico. From north to south, San Diego County extends from the southern borders of Orange and Riverside counties to the Mexico–U.S. border and the municipalities of Tijuana and Tecate in Baja California. From west to east, San Diego County stretches from the Pacific Ocean to its boundary with Imperial County, which separated from it in 1907.

Anza-Borrego Desert State Park (/ˈænzə bəˈreɪɡoʊ/, AN-zə bə-RAY-goh) is a California State Park located within the Colorado Desert of Southern California, United States. Created in 1932, the park takes its name from 18th century Spanish explorer Juan Bautista de Anza and borrego, a Spanish word for sheep. With 650,000 acres (260,000 ha) that includes one-fifth of San Diego County, it is the largest state park in California and the third largest state park nationally.

The park occupies eastern San Diego County and reaches into Imperial and Riverside counties, enveloping two communities: Borrego Springs, which is home to the park's headquarters, and Shelter Valley.

Calexico (/kəˈlɛksɪkoʊ/) is a city in southern Imperial County, California. Situated on the Mexican border, it is linked economically with the much larger city of Mexicali, the capital of the Mexican state of Baja California. It is about 122 miles (196 km) east of San Diego and 62 miles (100 km) west of Yuma, Arizona. Calexico, along with six other incorporated Imperial County cities, forms part of the larger populated area known as the Imperial Valley. First explored by Europeans in the 18th century, Calexico began as a small tent community which was ultimately incorporated in 1908.

The Salton Sea is a shallow, landlocked, highly saline endorheic lake in Riverside and Imperial counties in Southern California. It lies on the San Andreas Fault within the Salton Trough, which stretches to the Gulf of California in Mexico. The lake is about 15 by 35 miles (24 by 56 km) at its widest and longest. A 2023 report put the surface area at 318 square miles (823.6 km). The Salton Sea became a resort destination in the 20th century, but saw die-offs of fish and birds in the 1980s due to contamination from farm runoff, and clouds of toxic dust in the current century as evaporation exposed parts of the lake bed.

Over millions of years, the Colorado River had flowed into the Imperial Valley and deposited alluvium (soil), creating fertile farmland, building up the terrain, and constantly moving its main course and river delta. For thousands of years, the river alternately flowed into the valley or diverted around it, creating either a salt lake called Lake Cahuilla or a dry desert basin, respectively. When the river diverted around the valley, the lake dried completely, as it did around 1580. Hundreds of archaeological sites have been found in this region, indicating possibly long-term Native American villages and temporary camps.

The U.S. state of California is divided into 58 counties. The state was first divided into 27 counties on February 18, 1850. These were further sub-divided to form sixteen additional counties by 1860. Another fourteen counties were formed through further subdivision from 1861 to 1893. The most recent county to form was Imperial County, in 1907. California is home to San Bernardino County, the largest county in the contiguous United States, as well as Los Angeles County, the most populous county in the United States.

The counties of California are local arms of the State of California, described by the Supreme Court of California as agents ("the county is merely a political subdivision of state government, exercising only the powers of the state, granted by the state…'") and the property they hold is held on behalf of all the people of the state. As such, the State Legislature may delegate any of the functions of the State to the counties but likewise can reassume any delegated duties.

The saguaro (/səˈ(ɡ)wɑːroʊ/ sə-(G)WAR-oh, Spanish: [saˈɣwaɾo]; Carnegiea gigantea) is a tree-like cactus species in the monotypic genus Carnegiea that can grow to be over 12 meters (40 feet) tall. It is native to the Sonoran Desert in Arizona, the Mexican state of Sonora, and the Whipple Mountains and Imperial County areas of California. Saguaro typically grow at elevations ranging from sea level to 4,500', although they may be found at up to 5,000'. The saguaro blossom is the state wildflower of Arizona. Its scientific name is given in honor of Andrew Carnegie. In 1933, Saguaro National Park, near Tucson, Arizona, was designated to help protect this species and its habitat.

Saguaros have a relatively long lifespan, often exceeding 150 years. They may grow their first side arm around 75–100 years of age, but some never grow any arms. Arms are developed to increase the plant's reproductive capacity, as more apices lead to more flowers and fruit. A saguaro can absorb and store considerable amounts of rainwater, visibly expanding in the process, while slowly using the stored water as needed. This characteristic enables the saguaro to survive during periods of drought. It is a keystone species, and provides food and habitat to a large number of species.

El Centro (Spanish for "The Center") is a city in and the county seat of Imperial County, California, United States. El Centro is the most populous city in the Imperial Valley, the east anchor of the Southern California Border Region, and the core urban area and principal city of the El Centro metropolitan area which encompasses all of Imperial County. El Centro is also the most populous U.S. city to lie entirely below sea level (−42 feet or −13 meters). The city, located in southeastern California, is 113 miles (182 km) from San Diego and less than 20 miles (32 km) from the Mexican city of Mexicali.

The city was founded in 1906 by W. F. Holt and C.A. Barker, who purchased the land on which El Centro was eventually built for about $40 per acre ($100 per hectare) and invested $100,000 ($3,500,000 in 2024 dollars) in improvements. The modern city is home to retail, transportation, wholesale, and agricultural industries. There are also two international border crossings nearby for commercial and noncommercial vehicles. El Centro's census population as of 2020 was 44,322, up from 42,598 at the 2010 Census.