Overall Geography and Population in Orange County

Orange County is a large suburban county located between Los Angeles and San Diego Counties in Southern California. The county is comprised of 34 cities and covers approximately 798 square miles. With nearly 3.2 million residents, Orange County has a population larger than 22 U.S. states and is the sixth largest county in the United States, exceeded in population only by Los Angeles County, California; Cook County, Illinois; Harris County, Texas; Maricopa County, Arizona, and San Diego County, California.18

Between 198019 and 201820 Orange County’s total population increased by 62.4% from 1.9 to just over 3.2 million. As of July 1, 2018, Orange County’s population density stood at 4,037 persons per square mile. The density of cities within Orange County vary from a low of 454 persons per square mile in unincorporated areas to highs of 13,157 in Stanton, 12,528 in Santa Ana, and 9,828 in Garden Grove.21

The data presented throughout this chapter can be found in tables at the end of the chapter. Tables include all data since reporting began even though data by year presented in this chapter only includes the previous 10 years (2009 to 2018).

Figure 2.1 shows a map of the population in Orange County by city in 2018. As shown:

 The most populous cities are Santa Ana and Anaheim, with over 300,000 residents.  Cities with between 100,000 and 299,999 include Costa Mesa, Fullerton, Garden Grove, Huntington Beach, Irvine,

and the City of Orange.

Figure 2.1. 2018 Orange County Population by City

18 U.S. Census Bureau, American Community Survey, 2018. 19 State of California, Department of Finance, E-6 County Population Estimates and Components of Change — July 1, 1970–1990, Sacramento, California. 20 State of California, Department of Finance, California County Population Estimates and Components of Change by Year, July 1, 2010-2018. Sacramento, California, December 2018. 21 State of California, Department of Finance, E-4 Population Estimates for Cities, Counties, and the State, 2011-2018, with 2010 Census Benchmark. Sacramento, California, May 2018. Health Promotion and Community Planning Division 55 HIV/AIDS Surveillance and Monitoring