Yucaipa (Serrano: Yukaipa't) is a city located 10 miles (16 km) east of San Bernardino, in San Bernardino County, California, United States. The population was 54,542 at the 2020 census, up from 51,367 at the 2010 census. Yucaipa has the distinction of being the longtime home to a large population of Serrano Native Americans.

Prior to the Spanish colonization of the Americas and the arrival of European settlers from Mexico, the Yucaipa Valley was known as Yukaipa't, which meant "green valley" in the Serrano American Language. The land was home to the Serrano Native Americans for thousands of years. Today, some of their descendants are enrolled in the San Manuel Band of Mission Indians.

Yucaipa Valley supported a large population of Serrano Native Americans. The fertile valley was watered by springs and creeks running out of the San Bernardino Mountains. The Serrano Americans lived in this location most of the year, but would make excursions into the mountains to gather acorns and other food items during their harvest season. The Rancheria is marked by California Historical Landmark #620.

Near the Rancheria is the Yucaipa Adobe, which is believed to be the oldest house in San Bernardino County. Diego Sepúlveda, nephew of Antonio María Lugo, built the Adobe in 1842 on land that was part of the Rancho San Bernardino granted in 1842 to the Lugos. It had formerly been land controlled by San Gabriel Mission. The Rancho suffered losses of cattle and horses from raids by Native Americans coming through Cajon Pass and Banning Pass from the deserts. Eventually, they sold the Rancho to Mormon settlers in September 1851. The Adobe's later owners included John Brown Sr., James W. Waters, and the Dunlap family; it was acquired by San Bernardino County in 1955. The site is marked by California Historical Landmark #528.

The nearby Oak Glen area is best known for its apple orchards, some of which are operated by the direct descendants of the original founders (the Parrish, Wilshire, Rivers, and Law families). The Parrish Pioneer Ranch and orchard were founded by Enoch Parrish in 1876, with the other families coming into the area later.

At 1:53 p.m. on June 16, 2005, Yucaipa experienced a 4.9 Mw earthquake that was centered four miles (6 km) north of the center of town. It had a maximum Mercalli intensity of VI (Strong) and was felt from downtown Los Angeles to some areas of San Diego. Three people were injured.

In 2016, Yucaipa broke ground on a multipurpose performing arts center on the corner of Acacia Avenue and California Street. Sitting on 2.7 acres (11,000 m2) in the heart of uptown, the 16,200 sq ft (1,510 m2) venue hosts a variety of events, including community theater, open-air concerts, dance, and other arts-related events. The performing arts center officially opened in Spring 2019.

Yucaipa is located in southern California, approximately 72 miles (116 km) east of Los Angeles. The city is approximately 2,600 ft (790 m) above sea level and is bordered by Redlands to its west and Calimesa to its south. The unincorporated communities of Cherry Valley, Mentone and Oak Glen collectively account for Yucaipa's northernmost outskirts.

According to the United States Census Bureau, the city has a total area of 27.8 square miles (72 km2), with 0.04 percent being water.

Yucaipa is home to Yucaipa Regional Park, Flag Hill Veterans Memorial Park, Seventh Street Park, "I" Street Park, Wildwood Park, Yucaipa Community Park, the Bryant Glen Sports Complex, the Rick McCowan Regional Soccer Complex, and Wildwood Canyon State Park.

According to the Köppen Climate Classification system, Yucaipa has a Mediterranean climate, abbreviated Csa on climate maps.

At the 2010 census Yucaipa had a population of 51,367. The population density was 1,841.5 inhabitants per square mile (711.0/km2). The racial makeup of Yucaipa was 40,824 (79.5%) White (65.9% Non-Hispanic White), 837 (1.6%) African American, 485 (0.9%) Native American, 1,431 (2.8%) Asian, 74 (0.1%) Pacific Islander, 5,589 (10.9%) from other races, and 2,127 (4.1%) from two or more races. Hispanic or Latino of any race were 13,943 persons (27.1%).

The census reported that 50,813 people (98.9% of the population) lived in households, 227 (0.4%) lived in non-institutionalized group quarters, and 327 (0.6%) were institutionalized.

There were 18,231 households, 6,996 (38.4%) had children under the age of 18 living in them, 9,842 (54.0%) were opposite-sex married couples living together, 2,231 (12.2%) had a female householder with no husband present, 1,026 (5.6%) had a male householder with no wife present. There were 1,061 (5.8%) unmarried opposite-sex partnerships, and 114 (0.6%) same-sex married couples or partnerships. 4,198 households (23.0%) were one person and 1,970 (10.8%) had someone living alone who was 65 or older. The average household size was 2.79. There were 13,099 families (71.9% of households); the average family size was 3.29.

The age distribution was 13,444 people (26.2%) under the age of 18, 4,489 people (8.7%) aged 18 to 24, 12,536 people (24.4%) aged 25 to 44, 14,064 people (27.4%) aged 45 to 64, and 6,834 people (13.3%) who were 65 or older. The median age was 37.8 years. For every 100 females, there were 96.8 males. For every 100 females age 18 and over, there were 92.5 males.

There were 19,642 housing units at an average density of 704.2 per square mile, of the occupied units 13,503 (74.1%) were owner-occupied and 4,728 (25.9%) were rented. The homeowner vacancy rate was 3.0%; the rental vacancy rate was 9.0%. 37,165 people (72.4% of the population) lived in owner-occupied housing units and 13,648 people (26.6%) lived in rental housing units.

Since the city incorporated in 1989, it has experienced a significant level of growth. At the 2000 census Yucaipa had 41,207 residents, 15,193 households, and 10,680 families. The population density was 1,483.4 inhabitants per square mile (572.7/km2). There were 16,112 housing units at an average density of 580.0 per square mile (223.9/km2). The racial makeup was 85.2% White, 0.9% African American, 1.1% Native American, 1.2% Asian, 0.1% Pacific Islander, 8.0% from other races, and 3.5% from two or more races. Hispanics or Latinos constitute 18.4%.

Of the 15,193 households 35.4% had children under the age of 18; 54.2% were married couples; 11.6% had a female householder; and 29.7% were non-families. 25.3% of households were one person and 13.4% of those were 65 or older. The average household size was 2.7 and the average family size was 3.2.

The age distribution was 28.5% under the age of 18, 7.6% from 18 to 24, 27.2% from 25 to 44, 21.2% from 45 to 64, and 15.5% 65 or older. The median age was 37 years. For every 100 females, there were 93.5 males. For every 100 females age 18 and over, there were 88.4 males.

The median household income was $39,144 and the median family income was $48,683. Males had a median income of $40,480 versus $25,957 for females. The per capita income for the city was $18,949. About 8.8% of families and 11.2% of the population were below the poverty line, including 13.2% of those under age 18 and 7.2% of those age 65 or over.

In the California State Legislature, Yucaipa is in the 19th Senate District, represented by Republican Rosilicie Ochoa Bogh, and in the 47th Assembly District, represented by Republican Greg Wallis.

In the California's 23rd congressional district, represented by Republican Jay Obernolte.

From November 1999, Richard (Dick) D. Riddell was the longest-serving mayor (and the oldest, at age 88) in Yucaipa's history. In November 2012, at the request of newly sworn councilman Bobby Duncan, Denise Hoyt was named the new Mayor. As of 2020[update], Yucaipa's City Council was composed of Mayor Greg Bogh, Mayor Pro Tem Bobby Duncan, Councilman David Avila, Councilman Jon Thorp and Councilman Justin Beaver. Beaver was elected to Yucaipa's 4th district as the youngest councilman in the city's history at 32 years of age.

The Yucaipa-Calimesa Joint Unified School District serves both cities, with the following schools:

The city is also home to Crafton Hills College, operated by the San Bernardino Community College District.

The San Bernardino County Sheriff's Department serves Yucaipa—including the nearby unincorporated towns of Mentone, Oak Glen, Forest Falls, Angelus Oaks, and Mountain Home Village—from its regional station at 34282 Yucaipa Boulevard (a larger replacement opened on July 1, 2014, next to City Hall at 34144 Yucaipa Boulevard). Since there is no official jail facility at this station, suspects are booked at either Central Jail in downtown San Bernardino or the West Valley Detention Center in Rancho Cucamonga.

Yucaipa has contracted operation of its fire department to the California Department of Forestry and Fire Protection (now known as "Cal Fire") which serves the city from three stations: the 33000 block of Yucaipa Boulevard, Bryant Street (in the "North Bench" area), and the southwest corner of Fifth Street and Wildwood Canyon Road. Cal-Fire also provides paramedic level emergency medical service while patient transport by ground is handled by American Medical Response.

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