| | Justin, TX | Northlake, TX | United States |
| Population | 4,441 | 5,294 | 329,725,481 |
| Female Population | 48.0% | 51.2% | 50.5% |
| Male Population | 52.0% | 48.8% | 49.5% |
| Median Age | 44.7 | 30.9 | 38.4 |
| space3 | | | |
| Population - 2010 | 3,261 | 1,871 | 309,327,143 |
| Population - 2000 | 1,891 | 921 | 285,036,114 |
| Population - 1990 | 1,234 | 250 | 251,960,433 |
| Pop. 2000 to Now | 149.5% | 372.8% | 15.6% |
| Pop. 1990 to Now | 282.3% | 1,641.6% | 30.8% |
| space4 | | | |
| Population Density | 1,869.9 | 313.9 | 93.4 |
| Land Area | 2.4 | 16.9 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Justin, TX | Northlake, TX | United States |
| Age 0 to 4 | 5.4% | 7.7% | 5.9% |
| Age 5 to 9 | 8.4% | 15.2% | 6.1% |
| Age 10 to 14 | 6.8% | 5.9% | 6.6% |
| Age 15 to 17 | 1.8% | 2.5% | 3.9% |
| Age 18 to 20 | 0.1% | 1.6% | 4.0% |
| Age 21 to 24 | 4.5% | 4.7% | 5.2% |
| Age 25 to 34 | 8.2% | 21.0% | 13.8% |
| Age 35 to 44 | 15.8% | 13.5% | 12.9% |
| Age 45 to 54 | 21.6% | 11.9% | 12.6% |
| Age 55 to 59 | 5.1% | 6.8% | 6.7% |
| Age 60 to 64 | 7.0% | 4.2% | 6.3% |
| Age 65 to 74 | 7.0% | 3.3% | 9.6% |
| Age 75 to 84 | 5.2% | 1.6% | 4.5% |
| Age 85 and over | 3.1% | 0.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Justin, TX | Northlake, TX | United States |
| White | 67.6% | 59.3% | 59.4% |
| Black | 13.4% | 5.7% | 12.2% |
| Asian | 0.9% | 2.3% | 5.6% |
| Native American | 0.1% | 0.8% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 4.5% | 5.7% | 3.2% |
| Hispanic | 13.6% | 26.1% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Justin, TX | Northlake, TX | United States |
| Married Population | 62.7% | 59.4% | 49.8% |
| Currently Married | 61.6% | 58.7% | 48.0% |
| Married but Separated | 1.2% | 0.7% | 1.8% |
| Single Population | 37.3% | 40.6% | 50.2% |
| Never Married | 13.8% | 22.8% | 33.8% |
| Divorced | 12.3% | 15.2% | 10.8% |
| Widowed | 11.1% | 2.6% | 5.6% |
| space5 | | | |
| Household Size | 2.39 | 2.61 | 2.60 |
| Households | 1,815 | 2,029 | 124,010,992 |
| Family Households | 1,234 | 1,385 | 80,755,759 |
| Married couple, w/children | 31.0% | 43.0% | 30.5% |
| Married couple, no children | 52.3% | 34.4% | 42.9% |
| Non Family Households | 581 | 644 | 43,255,233 |
| Single householder, w/children | 6.9% | 13.9% | 15.8% |
| Single householder, no children | 9.8% | 8.7% | 10.8% |