Lake San Marcos, California Demographics & Population 2026

Population Overview

Lake San Marcos is a small community located in California, within San Diego County. The total population is 4,693. It ranks as the 677th most populous out of 1,570 Census-designated places in California.

Age Demographics

The median age in Lake San Marcos is 63.0 years. This is 66% higher than the state median of 37.9 years. Only 8.3% of residents are under 18, indicating fewer families with children. 26.9% of residents are 75 or older, suggesting a significant retirement-age population with implications for healthcare services and senior housing.

Economy, Income & Housing

The median household income in Lake San Marcos is $89,851. This is 9% lower than the state median of $99,122. It is also 11% higher than the national median of $80,734. The poverty rate stands at 6.0%. This is 50% lower than the state poverty rate of 12.0%. The unemployment rate is 4.1%. This is 38% lower than the state rate of 6.6%. The median home value is $917,000. Housing costs are 25% higher than the state median of $734,700. The home-value-to-income ratio of 10.2x suggests that housing affordability is a significant concern for many residents. 79.0% of occupied housing units are owner-occupied. This homeownership rate is 42% higher than the state average of 55.9%.

Race & Ethnicity

The largest racial or ethnic group in Lake San Marcos is White (non-Hispanic), making up 66.1% of the population. Hispanic or Latino residents account for 22.3%. The White (non-Hispanic) population is significantly higher than the state average (66.1% vs 33.8%). The Black or African American population (0.4%) is well below the state average of 5.2%. The Asian population (5.2%) is well below the state average of 15.3%.

Education

35.6% of residents aged 25 and older hold a bachelor's degree or higher. This is 4% lower than the state rate of 37.1%. Nationally, 35.7% of adults hold at least a bachelor's degree. The high school graduation rate (or equivalent) is 85.4%.

Data Sources & Methodology

All demographic data for Lake San Marcos, California is sourced from the U.S. Census Bureau's American Community Survey (ACS) 2020–2024 5-Year Estimates. The ACS collects data from approximately 3.5 million households annually and pools five years of responses so that even small communities can be measured, though the margin of error widens as the population falls. Comparisons are made against California state averages and national averages calculated from the same dataset. Rankings reflect the city's position among all 1,570 Census-designated places in California. Read more about how these figures are produced on our methodology page, or visit data.census.gov for official data.