Population of Counties in California (2018)
Not surprisingly, California's Los Angeles County is the largest county in the state, as well as the nation, with a huge population of 10,150,558 that continues to grow – the most recent census shows that its population has increased by 3.32% since the last census. A number of other Californian counties also boast large populations, although they look small in comparison to Los Angeles County. San Diego County has a population of 3,317,200 and a growth rate of 6.88%, while neighboring Orange County has 3,177,703 residents and a growth rate of 5.32%.
The smallest county in California is Alpine County, with its population of just 1,057. This total represents a decrease of 8.96% since the last census. Sierra County and Modoc County follow, with populations of 2,964 and 8,941, respectively, and negative growth rates of 7.98% and 7.82%. Many other counties have fewer than fifty thousand residents, such as Trinity County (12,839), Del Norte County (27,450), and Siskiyou County (43,511) – each of these counties also show negative growth rates. However, one smaller county, San Benito County (59,335) has increased its population by an impressive 6.85% since the last census.
Alameda County, with its sizeable population of 1,653,236, has shown the largest population growth, with an increase of 9.24% – this can perhaps be attributed to its proximity to San Francisco. Indeed, San Francisco county also has a substantial population growth of 8.73% and 876,103 residents. Lassen County has the highest negative growth, with its 30,944 residents representing a significant decrease of 11.16%.