Lake Mathews, CA has a population of 5,956 and is the 5,781st largest city in the United States. The population density is 374 per sq mi which is 61% higher than the California average and 313% higher than the national average. The median age in Lake Mathews is 36 which is approximately 1% higher than the California average of 36. In Lake Mathews, 50% of the population over 15 years of age are married, 71% speak English and 26% speak Spanish. 65% of Lake Mathews residents were born in California, 23% were born out of state, 1% were born outside of the United States and 11% were foreign born.