Santa Ana is the county seat and second most populous city in Orange County, California. The United States Census Bureau estimated its 2011 population at 329,427, making Santa Ana the 57th most-populous city in the United States.
Santa Ana is located in Southern California, adjacent to the Santa Ana River, about 10 miles (16 km) away from the California coast. Founded in 1869, the city is part of the Greater Los Angeles Area, the second largest metropolitan area in the United States with almost 18 million residents in 2010. Santa Ana is a very densely populated city, ranking fourth nationally in that regard among cities of over 300,000 residents (trailing only New York City, San Francisco, and Boston). In 2011 Forbes ranked Santa Ana the fourth-safest city of over 250,000 residents in the United States.
Santa Ana lends its name to the Santa Ana Freeway (I-5), which runs through the city. It also shares its name with the nearby Santa Ana Mountains, and the Santa Ana winds, which have historically fueled seasonal wildfires throughout Southern California. The current Office of Management and Budget (OMB) metropolitan designation for the Orange County Area is Santa Ana–Anaheim–Irvine, California.
The 2010 United States Census reported that Santa Ana had a population of 324,528. The population density was 11,793.3 people per square mile (4,553.4/km²). The racial makeup of Santa Ana was 148,838 (45.9%) White (9.2% Non-Hispanic White), 4,856 (1.5%) African American, 3,260 (1.0%) Native American, 34,138 (10.5%) Asian, 976 (0.3%) Pacific Islander, 120,789 (37.2%) from other races, and 11,671 (3.6%) from two or more races. Hispanic or Latino of any race were 253,928 persons (78.2%).
The census reported that 319,870 people (98.6% of the population) lived in households, 1,415 (0.4%) lived in non-institutionalized group quarters, and 3,243 (1.0%) were institutionalized.
There were 73,174 households, out of which 41,181 (56.3%) had children under the age of 18 living in them, 41,389 (56.6%) were opposite-sex married couples living together, 11,808 (16.1%) had a female householder with no husband present, 6,451 (8.8%) had a male householder with no wife present. There were 4,933 (6.7%) unmarried opposite-sex partnerships, and 556 (0.8%) same-sex married couples or partnerships. 9,254 households (12.6%) were made up of individuals and 3,378 (4.6%) had someone living alone who was 65 years of age or older. The average household size was 4.37. There were 59,648 families (81.5% of all households); the average family size was 4.54.
The age distribution of the population was as follows: 99,678 people (30.7%) under the age of 18, 39,165 people (12.1%) aged 18 to 24, 102,399 people (31.6%) aged 25 to 44, 61,375 people (18.9%) aged 45 to 64, and 21,911 people (6.8%) who were 65 years of age or older. The median age was 29.1 years. For every 100 females, there were 104.4 males. For every 100 females age 18 and over, there were 104.6 males.
There were 76,896 housing units at an average density of 2,794.4 per square mile (1,078.9/km²), of which 34,756 (47.5%) were owner-occupied, and 38,418 (52.5%) were occupied by renters. The homeowner vacancy rate was 1.9%; the rental vacancy rate was 4.9%. 154,045 people (47.5% of the population) lived in owner-occupied housing units and 165,825 people (51.1%) lived in rental housing units.
During 2009–2013, Santa Ana had a median household income of $53,335, with 21.5% of the population living below the federal poverty line.