| | San Leon, TX | La Marque, TX | United States |
| Population | 5,144 | 18,065 | 329,725,481 |
| Female Population | 41.9% | 51.1% | 50.5% |
| Male Population | 58.1% | 49.0% | 49.5% |
| Median Age | 42.5 | 39.2 | 38.4 |
| space3 | | | |
| Population - 2010 | 3,913 | 14,569 | 309,327,143 |
| Population - 2000 | 4,365 | 13,682 | 285,036,114 |
| Population - 1990 | 3,328 | 14,120 | 251,960,433 |
| Pop. 2000 to Now | 20.4% | 28.9% | 15.6% |
| Pop. 1990 to Now | 57.9% | 24.9% | 30.8% |
| space4 | | | |
| Population Density | 1,083.0 | 1,297.4 | 93.4 |
| Land Area | 4.8 | 13.9 | 3,531,905.4 |
| Water Area | 0.3 | 0.3 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | San Leon, TX | La Marque, TX | United States |
| Age 0 to 4 | 3.9% | 5.5% | 5.9% |
| Age 5 to 9 | 9.4% | 7.2% | 6.1% |
| Age 10 to 14 | 1.9% | 6.8% | 6.6% |
| Age 15 to 17 | 2.2% | 2.8% | 3.9% |
| Age 18 to 20 | 3.1% | 2.5% | 4.0% |
| Age 21 to 24 | 1.1% | 6.2% | 5.2% |
| Age 25 to 34 | 15.5% | 13.1% | 13.8% |
| Age 35 to 44 | 15.5% | 13.4% | 12.9% |
| Age 45 to 54 | 14.8% | 13.3% | 12.6% |
| Age 55 to 59 | 10.6% | 6.4% | 6.7% |
| Age 60 to 64 | 5.4% | 8.2% | 6.3% |
| Age 65 to 74 | 13.5% | 8.8% | 9.6% |
| Age 75 to 84 | 2.4% | 4.4% | 4.5% |
| Age 85 and over | 0.7% | 1.5% | 1.9% |
| space1 | | | |
| Race | | | |
| | San Leon, TX | La Marque, TX | United States |
| White | 55.2% | 33.3% | 59.4% |
| Black | 0.7% | 29.7% | 12.2% |
| Asian | 2.1% | 3.6% | 5.6% |
| Native American | 0.0% | 1.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.2% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 2.5% | 0.8% | 3.2% |
| Hispanic | 39.3% | 31.4% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | San Leon, TX | La Marque, TX | United States |
| Married Population | 59.8% | 50.6% | 49.8% |
| Currently Married | 55.3% | 48.3% | 48.0% |
| Married but Separated | 4.5% | 2.4% | 1.8% |
| Single Population | 40.2% | 49.4% | 50.2% |
| Never Married | 22.8% | 29.6% | 33.8% |
| Divorced | 14.0% | 13.0% | 10.8% |
| Widowed | 3.3% | 6.8% | 5.6% |
| space5 | | | |
| Household Size | 2.40 | 2.63 | 2.60 |
| Households | 2,145 | 6,823 | 124,010,992 |
| Family Households | 1,570 | 4,459 | 80,755,759 |
| Married couple, w/children | 24.2% | 31.5% | 30.5% |
| Married couple, no children | 51.0% | 38.8% | 42.9% |
| Non Family Households | 575 | 2,364 | 43,255,233 |
| Single householder, w/children | 11.5% | 17.1% | 15.8% |
| Single householder, no children | 13.3% | 12.6% | 10.8% |