Census-designated place · California
Lake San Marcos, California
Lake San Marcos, census-designated place, in San Diego County, California. Lake San Marcos had 4,693 people in the ACS 2020-2024 5-year estimates (±708). GEOID 0639724.
Residents, 2020-2024
4,693
±708 (90% margin)
2020 Census count: 5,328
Median household income
$89,851
±$17,454 (90% margin)
California: $99,122
Median home value
$917,000
±$70,499 (90% margin)
California: $734,700
Median gross rent
$2,585
±$214 (90% margin)
California: $2,036
Where is Lake San Marcos and what county is it in?
Lake San Marcos is a census-designated place: an unincorporated community the Census Bureau draws for counting, with no city government of its own, in San Diego County, California. It covers 1.7 square miles of land, 3,121 residents per square mile in 2020.
Lake San Marcos is in the San Diego-Chula Vista-Carlsbad, CA metropolitan statistical area (Census Bureau delineation, July 2023).
Source: 2024 Gazetteer and 2020 place-by-county files, U.S. Census Bureau · Census reference files
How many people live in Lake San Marcos, and is it growing?
The 2020-2024 American Community Survey puts Lake San Marcos's population at 4,693 (±708). The 2020 Census counted 5,328 residents.
The Census Bureau publishes yearly population estimates for incorporated places only; Lake San Marcos is a census-designated place, so its figures come from the ACS and the 2020 Census.
| Measure | Lake San Marcos | San Diego County | Change since 2015-2019 |
|---|---|---|---|
| Total population | 4,693 ±708 | 3,288,774 | no clear change |
| Households | 2,000 ±237 | 1,171,278 | −376 |
| Average household size | 2.27 ±0.27 | 2.72 | no clear change |
| Housing units | 2,117 ±251 | 1,250,641 | −618 |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026); Census PEP Vintage 2025 (SUB-EST2025, CO-EST2025); 2020 Census P.L. 94-171 · Check it at data.census.gov
Who lives in Lake San Marcos?
The median resident of Lake San Marcos is 63.0 years old; 8.3% are under 18 and 46.7% are 65 or older. The largest group is non-Hispanic white residents at 66.1%, then Hispanic or Latino residents (of any race) at 22.3%. 21.5% of residents were born outside the United States.
| Measure | Lake San Marcos | San Diego County | Change since 2015-2019 |
|---|---|---|---|
| Median age | 63.0 ±3.4 | 37.3 | no clear change |
| Under 18 years | 8.3% ±2.2 pts | 20.9% | – |
| 65 years and over | 46.7% ±6.7 pts | 15.4% | – |
| Male | 45.7% ±3.0 pts | 50.5% | – |
| Hispanic or Latino (any race) | 22.3% ±10.1 pts | 34.6% | no clear change |
| White alone, not Hispanic | 66.1% ±9.7 pts | 42.4% | no clear change |
| Black or African American alone, not Hispanic | 0.4% ±0.4 pts | 4.4% | – |
| Asian alone, not Hispanic | 5.2% ±2.8 pts | 12.1% | no clear change |
| American Indian and Alaska Native alone, not Hispanic | 0.0% ±0.9 pts | 0.2% | – |
| Native Hawaiian and Other Pacific Islander alone, not Hispanic | 0.0% ±0.9 pts | 0.4% | – |
| Two or more races, not Hispanic | 5.8% ±3.0 pts | 5.3% | – |
| Some other race alone, not Hispanic | 0.3% ±0.5 pts | 0.6% | – |
| Born outside the United States | 21.5% ±5.6 pts | 22.8% | no clear change |
| Speak a language other than English at home (age 5+) | 28.7% ±10.2 pts | 37.3% | – |
| Civilian veterans (age 18+) | 8.6% ±2.3 pts | 7.3% | – |
| With a disability | 18.4% ±4.3 pts | 11.1% | – |
| No health insurance coverage | 7.3% ±3.3 pts | 6.4% | – |
| High school graduate or higher (age 25+) | 85.4% ±6.0 pts | 89.1% | – |
| Bachelor's degree or higher (age 25+) | 35.6% ±6.5 pts | 43.2% | no clear change |
| Graduate or professional degree (age 25+) | 14.3% ±4.5 pts | 17.2% | – |
| Lived in the same house a year earlier | 91.3% ±3.7 pts | 87.2% | – |
| Moved from another state in the past year | 0.6% ±0.7 pts | 2.2% | – |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profiles DP02, DP05) · Check it at data.census.gov
What do households in Lake San Marcos earn?
Half of Lake San Marcos's 2,000 households earn less than $89,851 a year (±$17,454), against $106,268 in San Diego County and $99,122 in California. In 2015-2019 it was $88,515 in 2024 dollars; the margins of error cannot tell the two periods apart. 6.0% of residents live below the poverty line.
| Measure | Lake San Marcos | San Diego County | Change since 2015-2019 |
|---|---|---|---|
| Median household income | $89,851 ±$17,454 | $106,268 | no clear change |
| Mean household income | $120,348 ±$18,018 | $141,250 | – |
| Per capita income | $53,343 ±$8,396 | $51,976 | no clear change |
| People below the poverty line | 6.0% ±2.6 pts | 10.3% | – |
| Children under 18 below the poverty line | 6.2% ±9.8 pts | 11.8% | – |
| Households receiving SNAP | 5.4% ±2.9 pts | 9.9% | – |
| Households with a computer | 98.1% ±1.6 pts | 97.6% | – |
| Households with a broadband subscription | 93.7% ±3.2 pts | 94.9% | – |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP03) · Check it at data.census.gov
What does housing cost in Lake San Marcos?
Owners occupy 79.1% of Lake San Marcos's occupied homes and renters 21.0%. The median owner-occupied home is valued at $917,000 by its owner (±$70,499). The median renter pays $2,585 a month including utilities, and 38.6% of renters pay 35% or more of their income on rent.
| Measure | Lake San Marcos | San Diego County | Change since 2015-2019 |
|---|---|---|---|
| Median home value (owner-occupied) | $917,000 ±$70,499 | $854,700 | +$175,261 |
| Median gross rent | $2,585 ±$214 | $2,246 | no clear change |
| Renters paying 35% or more of income on rent | 38.6% ±15.6 pts | 47.7% | no clear change |
| Median monthly owner costs, with a mortgage | $2,701 ±$190 | $3,184 | – |
| Owner-occupied homes | 79.1% ±5.0 pts | 54.6% | no clear change |
| Renter-occupied homes | 21.0% ±5.0 pts | 45.4% | – |
| Housing units | 2,117 ±251 | 1,250,641 | −618 |
| Homeowner vacancy rate | 0.0% ±2.6 pts | 0.7% | – |
| Rental vacancy rate | 13.3% ±14.0 pts | 3.9% | – |
| Single-family detached homes | 59.7% ±7.2 pts | 50.0% | – |
| Mobile homes | 0.0% ±2.0 pts | 3.3% | – |
| Built 2020 or later | 0.0% ±2.0 pts | 1.4% | – |
| Built 2010 to 2019 | 4.5% ±1.8 pts | 6.9% | – |
| Built 1939 or earlier | 0.0% ±2.0 pts | 4.0% | – |
| Households with no vehicle | 3.7% ±2.3 pts | 5.5% | – |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP04) · Check it at data.census.gov
How do people in Lake San Marcos work and get to work?
74.0% of Lake San Marcos's workers drive alone and 23.5% work from home. The average trip to work takes 23.5 minutes.
| Measure | Lake San Marcos | San Diego County | Change since 2015-2019 |
|---|---|---|---|
| In the labor force (age 16+) | 46.2% ±7.1 pts | 66.2% | – |
| Unemployment rate | 4.1% ±3.5 pts | 6.1% | – |
| Drove alone to work | 74.0% ±9.2 pts | 65.9% | – |
| Carpooled | 2.0% ±2.2 pts | 8.1% | – |
| Public transportation | 0.0% ±2.3 pts | 1.9% | – |
| Walked | 0.0% ±2.3 pts | 3.2% | – |
| Worked from home | 23.5% ±8.2 pts | 18.7% | +13.3 pts |
| Mean travel time to work | 23.5 min ±3.2 | 25.5 min | no clear change |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) (Data Profile DP03) · Check it at data.census.gov
What census tracts are in Lake San Marcos?
No census tract lies mostly in Lake San Marcos; 5 tracts reach into it (2020 census blocks).
| Tract | Residents, 2020-2024 | Median household income |
|---|---|---|
| Tract 200.26San Diego County | 4,447 | $135,238 |
| Tract 200.42San Diego County | 4,759 | $110,313 |
| Tract 200.44San Diego County | 9,056 | $213,196 |
| Tract 200.19San Diego County | 7,253 | $89,875 |
| Tract 200.31San Diego County | 6,519 | $116,982 |
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026); 2020 block assignment files (tract share = share of the tract's census blocks in Lake San Marcos) · Census block assignment files
How does Lake San Marcos compare with other places in California?
Lake San Marcos ranks 566th of 1,037 places in California with 1,000 or more residents and a reliable estimate, by median household income.
| Measure | Rank | Of |
|---|---|---|
| Population (ACS 2020-2024) | 677th | 1,076 |
| Residents per square mile | 434th | 1,077 |
| Median household income | 566th | 1,037 |
| Per capita income | 348th | 1,073 |
| Median home value | 270th | 1,054 |
| Median gross rent | 173rd | 987 |
| Poverty rate | 701st | 836 |
| Bachelor's degree or higher | 423rd | 988 |
| Median age | 25th | 1,075 |
| Owner-occupied share | 260th | 1,064 |
| Work from home | 221st | 822 |
| Travel time to work | 803rd | 1,069 |
Lake San Marcos's figures with every place in California (CSV)
Every place in California, sortable · Compare Lake San Marcos with other places
Source: PlainCities ranks computed from the American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026) and PEP Vintage 2025 · How ranks are computed
How reliable are the figures for Lake San Marcos?
15 of the 57 figures for Lake San Marcos on this page carry a coefficient of variation over 40% and are marked with a ring: they come from a small sample, so read them as rough.
The American Community Survey samples about one household in eight over five years, so every figure is an estimate with a 90% margin of error (shown under each value). A ring marks an estimate whose coefficient of variation is over 40%. A change is called only when the gap between the two periods is larger than their combined 90% margin (the square root of the sum of the two squared margins), the Census Bureau's test. How to read a margin of error.
Source: American Community Survey 2020-2024 5-year estimates, U.S. Census Bureau (released January 2026): margins of error as published · ACS technical documentation
How these figures are made: methodology and release checks · reading a margin of error · every state · corrections
Not on this page: crime, weather and schools for Lake San Marcos are other agencies' records. Crime: the FBI's Crime Data Explorer · climate: NOAA's U.S. Climate Normals · schools: the National Center for Education Statistics' school search.