| | San Leon, TX | Galveston, TX | United States |
| Population | 5,144 | 53,092 | 329,725,481 |
| Female Population | 41.9% | 49.4% | 50.5% |
| Male Population | 58.1% | 50.6% | 49.5% |
| Median Age | 42.5 | 40 | 38.4 |
| space3 | | | |
| Population - 2010 | 3,913 | 47,794 | 309,327,143 |
| Population - 2000 | 4,365 | 57,247 | 285,036,114 |
| Population - 1990 | 3,328 | 59,070 | 251,960,433 |
| Pop. 2000 to Now | 20.4% | -12.5% | 15.6% |
| Pop. 1990 to Now | 57.9% | -15.2% | 30.8% |
| space4 | | | |
| Population Density | 1,083.0 | 1,290.2 | 93.4 |
| Land Area | 4.8 | 41.2 | 3,531,905.4 |
| Water Area | 0.3 | 168.2 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | San Leon, TX | Galveston, TX | United States |
| Age 0 to 4 | 3.9% | 4.6% | 5.9% |
| Age 5 to 9 | 9.4% | 4.2% | 6.1% |
| Age 10 to 14 | 1.9% | 4.5% | 6.6% |
| Age 15 to 17 | 2.2% | 2.8% | 3.9% |
| Age 18 to 20 | 3.1% | 4.9% | 4.0% |
| Age 21 to 24 | 1.1% | 7.0% | 5.2% |
| Age 25 to 34 | 15.5% | 15.4% | 13.8% |
| Age 35 to 44 | 15.5% | 11.7% | 12.9% |
| Age 45 to 54 | 14.8% | 11.5% | 12.6% |
| Age 55 to 59 | 10.6% | 7.2% | 6.7% |
| Age 60 to 64 | 5.4% | 7.2% | 6.3% |
| Age 65 to 74 | 13.5% | 12.5% | 9.6% |
| Age 75 to 84 | 2.4% | 4.6% | 4.5% |
| Age 85 and over | 0.7% | 1.8% | 1.9% |
| space1 | | | |
| Race | | | |
| | San Leon, TX | Galveston, TX | United States |
| White | 55.2% | 48.2% | 59.4% |
| Black | 0.7% | 15.8% | 12.2% |
| Asian | 2.1% | 2.7% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.2% | 0.1% | 0.2% |
| Other | 0.0% | 0.1% | 0.4% |
| Two or More Races | 2.5% | 1.8% | 3.2% |
| Hispanic | 39.3% | 31.1% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | San Leon, TX | Galveston, TX | United States |
| Married Population | 59.8% | 42.4% | 49.8% |
| Currently Married | 55.3% | 39.9% | 48.0% |
| Married but Separated | 4.5% | 2.6% | 1.8% |
| Single Population | 40.2% | 57.6% | 50.2% |
| Never Married | 22.8% | 37.9% | 33.8% |
| Divorced | 14.0% | 14.1% | 10.8% |
| Widowed | 3.3% | 5.5% | 5.6% |
| space5 | | | |
| Household Size | 2.40 | 2.12 | 2.60 |
| Households | 2,145 | 23,313 | 124,010,992 |
| Family Households | 1,570 | 12,404 | 80,755,759 |
| Married couple, w/children | 24.2% | 19.0% | 30.5% |
| Married couple, no children | 51.0% | 47.8% | 42.9% |
| Non Family Households | 575 | 10,909 | 43,255,233 |
| Single householder, w/children | 11.5% | 17.8% | 15.8% |
| Single householder, no children | 13.3% | 15.5% | 10.8% |