2020 census As of the
2020 census, Larkspur had a population of 13,064 and a population density of . The age distribution was 18.2% under the age of 18, 5.5% aged 18 to 24, 20.1% aged 25 to 44, 30.4% aged 45 to 64, and 25.8% who were 65 years of age or older. The median age was 49.2 years. For every 100 females there were 85.9 males, and for every 100 females age 18 and over there were 82.5 males age 18 and over. There were 6,459 housing units at an average density of , of which 6,102 (94.5%) were occupied. Of these, 48.6% were owner-occupied and 51.4% were occupied by renters. Overall, 5.5% of housing units were vacant. The homeowner vacancy rate was 0.5%, and the rental vacancy rate was 5.2%. The median household income in 2023 was $134,744, and the
per capita income was $103,235. About 3.4% of families and 7.1% of the population were below the poverty line.
2010 census At the
2010 census Larkspur had a population of 11,926. The population density was . The racial makeup of Larkspur was 10,311 (86.5%) White, 186 (1.6%) African American, 26 (0.2%) Native American, 563 (4.7%) Asian, 13 (0.1%) Pacific Islander, 343 (2.9%) from
other races, and 484 (4.1%) from two or more races. Hispanic or Latino of any race were 918 people (7.7%). The census reported that 11,803 people (99.0% of the population) lived in households, 42 (0.4%) lived in non-institutionalized group quarters, and 81 (0.7%) were institutionalized. There were 5,908 households, 1,314 (22.2%) had children under the age of 18 living in them, 2,266 (38.4%) were
opposite-sex married couples living together, 433 (7.3%) had a female householder with no husband present, 197 (3.3%) had a male householder with no wife present. There were 329 (5.6%)
unmarried opposite-sex partnerships, and 74 (1.3%)
same-sex married couples or partnerships. 2,502 households (42.3%) were one person and 1,009 (17.1%) had someone living alone who was 65 or older. The average household size was 2.00. There were 2,896 families (49.0% of households); the average family size was 2.77. The age distribution was 2,176 people (18.2%) under the age of 18, 466 people (3.9%) aged 18 to 24, 2,620 people (22.0%) aged 25 to 44, 4,103 people (34.4%) aged 45 to 64, and 2,561 people (21.5%) who were 65 or older. The median age was 48.5 years. For every 100 females, there were 81.9 males. For every 100 females age 18 and over, there were 78.0 males. There were 6,376 housing units at an average density of 1,966.1 per square mile, of the occupied units 2,898 (49.1%) were owner-occupied and 3,010 (50.9%) were rented. The homeowner vacancy rate was 1.5%; the rental vacancy rate was 7.1%. 6,494 people (54.5% of the population) lived in owner-occupied housing units and 5,309 people (44.5%) lived in rental housing units. ==Transportation==