| | San Carlos, TX | Longview, TX | United States |
| Population | 4,177 | 81,967 | 329,725,481 |
| Female Population | 50.7% | 51.0% | 50.5% |
| Male Population | 49.3% | 49.0% | 49.5% |
| Median Age | 28.7 | 34.7 | 38.4 |
| space3 | | | |
| Population - 2010 | 2,729 | 80,559 | 309,327,143 |
| Population - 2000 | 2,650 | 73,344 | 285,036,114 |
| Population - 1990 | 963 | 70,311 | 251,960,433 |
| Pop. 2000 to Now | 18.6% | 11.4% | 15.6% |
| Pop. 1990 to Now | 226.3% | 16.2% | 30.8% |
| space4 | | | |
| Population Density | 2,310.3 | 1,471.8 | 93.4 |
| Land Area | 1.8 | 55.7 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | San Carlos, TX | Longview, TX | United States |
| Age 0 to 4 | 9.2% | 6.9% | 5.9% |
| Age 5 to 9 | 9.4% | 6.7% | 6.1% |
| Age 10 to 14 | 10.8% | 7.5% | 6.6% |
| Age 15 to 17 | 6.4% | 4.4% | 3.9% |
| Age 18 to 20 | 5.1% | 4.3% | 4.0% |
| Age 21 to 24 | 5.2% | 5.8% | 5.2% |
| Age 25 to 34 | 15.8% | 14.8% | 13.8% |
| Age 35 to 44 | 12.0% | 12.0% | 12.9% |
| Age 45 to 54 | 11.2% | 10.9% | 12.6% |
| Age 55 to 59 | 4.7% | 5.6% | 6.7% |
| Age 60 to 64 | 2.8% | 6.2% | 6.3% |
| Age 65 to 74 | 5.8% | 9.0% | 9.6% |
| Age 75 to 84 | 0.6% | 4.0% | 4.5% |
| Age 85 and over | 1.0% | 2.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | San Carlos, TX | Longview, TX | United States |
| White | 3.7% | 52.3% | 59.4% |
| Black | 0.0% | 22.0% | 12.2% |
| Asian | 0.0% | 1.2% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.1% | 0.2% |
| Other | 0.0% | 0.2% | 0.4% |
| Two or More Races | 0.0% | 3.1% | 3.2% |
| Hispanic | 96.3% | 20.9% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | San Carlos, TX | Longview, TX | United States |
| Married Population | 52.8% | 45.6% | 49.8% |
| Currently Married | 49.9% | 43.4% | 48.0% |
| Married but Separated | 2.9% | 2.2% | 1.8% |
| Single Population | 47.2% | 54.4% | 50.2% |
| Never Married | 38.5% | 35.3% | 33.8% |
| Divorced | 4.2% | 13.2% | 10.8% |
| Widowed | 4.5% | 5.9% | 5.6% |
| space5 | | | |
| Household Size | 4.46 | 2.47 | 2.60 |
| Households | 937 | 31,730 | 124,010,992 |
| Family Households | 877 | 20,052 | 80,755,759 |
| Married couple, w/children | 37.7% | 27.7% | 30.5% |
| Married couple, no children | 30.9% | 37.9% | 42.9% |
| Non Family Households | 60 | 11,678 | 43,255,233 |
| Single householder, w/children | 22.7% | 24.4% | 15.8% |
| Single householder, no children | 8.7% | 9.9% | 10.8% |