Lakeside, CA has a population of 21,488 and is the 2,021st largest city in the United States. The population density is 3,117 per sq mi which is 1241% higher than the California average and 3340% higher than the national average. The median age in Lakeside is 38 which is approximately 6% higher than the California average of 36. In Lakeside, 56% of the population over 15 years of age are married, 86% speak English and 10% speak Spanish. 65% of Lakeside residents were born in California, 26% were born out of state, 1% were born outside of the United States and 7% were foreign born.