| | Terrell Hills, TX | Ennis, TX | United States |
| Population | 5,047 | 19,942 | 329,725,481 |
| Female Population | 49.2% | 51.2% | 50.5% |
| Male Population | 50.8% | 48.8% | 49.5% |
| Median Age | 40.2 | 33.9 | 38.4 |
| space3 | | | |
| Population - 2010 | 4,894 | 18,655 | 309,327,143 |
| Population - 2000 | 5,019 | 16,045 | 285,036,114 |
| Population - 1990 | 4,592 | 13,883 | 251,960,433 |
| Pop. 2000 to Now | 8.6% | 28.9% | 15.6% |
| Pop. 1990 to Now | 18.7% | 48.9% | 30.8% |
| space4 | | | |
| Population Density | 3,077.4 | 669.9 | 93.4 |
| Land Area | 1.6 | 29.8 | 3,531,905.4 |
| Water Area | 0.0 | 0.5 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Terrell Hills, TX | Ennis, TX | United States |
| Age 0 to 4 | 5.4% | 7.0% | 5.9% |
| Age 5 to 9 | 9.6% | 6.8% | 6.1% |
| Age 10 to 14 | 13.8% | 7.5% | 6.6% |
| Age 15 to 17 | 2.4% | 4.8% | 3.9% |
| Age 18 to 20 | 3.6% | 5.1% | 4.0% |
| Age 21 to 24 | 1.4% | 6.3% | 5.2% |
| Age 25 to 34 | 6.1% | 14.7% | 13.8% |
| Age 35 to 44 | 17.3% | 13.6% | 12.9% |
| Age 45 to 54 | 12.1% | 9.1% | 12.6% |
| Age 55 to 59 | 4.6% | 5.1% | 6.7% |
| Age 60 to 64 | 4.6% | 7.0% | 6.3% |
| Age 65 to 74 | 9.6% | 8.2% | 9.6% |
| Age 75 to 84 | 7.4% | 3.2% | 4.5% |
| Age 85 and over | 2.0% | 1.6% | 1.9% |
| space1 | | | |
| Race | | | |
| | Terrell Hills, TX | Ennis, TX | United States |
| White | 69.5% | 41.6% | 59.4% |
| Black | 0.2% | 11.1% | 12.2% |
| Asian | 4.4% | 0.0% | 5.6% |
| Native American | 0.2% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 0.0% | 2.6% | 3.2% |
| Hispanic | 25.6% | 44.4% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Terrell Hills, TX | Ennis, TX | United States |
| Married Population | 67.4% | 51.1% | 49.8% |
| Currently Married | 66.4% | 47.9% | 48.0% |
| Married but Separated | 1.0% | 3.2% | 1.8% |
| Single Population | 32.6% | 48.9% | 50.2% |
| Never Married | 20.8% | 31.1% | 33.8% |
| Divorced | 8.6% | 10.2% | 10.8% |
| Widowed | 3.2% | 7.6% | 5.6% |
| space5 | | | |
| Household Size | 3.06 | 2.85 | 2.60 |
| Households | 1,651 | 6,936 | 124,010,992 |
| Family Households | 1,271 | 5,151 | 80,755,759 |
| Married couple, w/children | 41.9% | 29.8% | 30.5% |
| Married couple, no children | 49.2% | 37.8% | 42.9% |
| Non Family Households | 380 | 1,785 | 43,255,233 |
| Single householder, w/children | 7.2% | 20.4% | 15.8% |
| Single householder, no children | 1.8% | 12.1% | 10.8% |