| | Erin, TN | Chattanooga, TN | United States |
| Population | 1,607 | 180,353 | 329,725,481 |
| Female Population | 46.3% | 52.5% | 50.5% |
| Male Population | 53.7% | 47.5% | 49.5% |
| Median Age | 42.8 | 36.7 | 38.4 |
| space3 | | | |
| Population - 2010 | 1,349 | 170,582 | 309,327,143 |
| Population - 2000 | 1,490 | 155,554 | 285,036,114 |
| Population - 1990 | 1,586 | 152,466 | 251,960,433 |
| Pop. 2000 to Now | -12.2% | 18.8% | 15.6% |
| Pop. 1990 to Now | -17.5% | 21.2% | 30.8% |
| space4 | | | |
| Population Density | 412.5 | 1,261.9 | 93.4 |
| Land Area | 3.9 | 142.9 | 3,531,905.4 |
| Water Area | 0.0 | 7.7 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Erin, TN | Chattanooga, TN | United States |
| Age 0 to 4 | 3.2% | 6.2% | 5.9% |
| Age 5 to 9 | 7.0% | 5.2% | 6.1% |
| Age 10 to 14 | 9.1% | 5.5% | 6.6% |
| Age 15 to 17 | 7.8% | 3.1% | 3.9% |
| Age 18 to 20 | 3.2% | 4.9% | 4.0% |
| Age 21 to 24 | 6.0% | 5.8% | 5.2% |
| Age 25 to 34 | 5.0% | 16.8% | 13.8% |
| Age 35 to 44 | 10.6% | 12.2% | 12.9% |
| Age 45 to 54 | 14.7% | 10.7% | 12.6% |
| Age 55 to 59 | 3.3% | 6.0% | 6.7% |
| Age 60 to 64 | 7.2% | 6.9% | 6.3% |
| Age 65 to 74 | 12.8% | 10.1% | 9.6% |
| Age 75 to 84 | 6.7% | 4.5% | 4.5% |
| Age 85 and over | 3.2% | 2.1% | 1.9% |
| space1 | | | |
| Race | | | |
| | Erin, TN | Chattanooga, TN | United States |
| White | 90.7% | 56.3% | 59.4% |
| Black | 9.1% | 30.3% | 12.2% |
| Asian | 0.0% | 2.7% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.3% | 0.4% |
| Two or More Races | 0.2% | 3.1% | 3.2% |
| Hispanic | 0.0% | 7.3% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Erin, TN | Chattanooga, TN | United States |
| Married Population | 35.1% | 39.6% | 49.8% |
| Currently Married | 33.4% | 37.3% | 48.0% |
| Married but Separated | 1.8% | 2.3% | 1.8% |
| Single Population | 64.9% | 60.4% | 50.2% |
| Never Married | 37.7% | 39.4% | 33.8% |
| Divorced | 18.8% | 13.7% | 10.8% |
| Widowed | 8.4% | 7.2% | 5.6% |
| space5 | | | |
| Household Size | 3.18 | 2.25 | 2.60 |
| Households | 459 | 76,508 | 124,010,992 |
| Family Households | 219 | 40,213 | 80,755,759 |
| Married couple, w/children | 27.9% | 22.9% | 30.5% |
| Married couple, no children | 62.6% | 40.7% | 42.9% |
| Non Family Households | 240 | 36,295 | 43,255,233 |
| Single householder, w/children | 5.0% | 21.2% | 15.8% |
| Single householder, no children | 4.6% | 15.3% | 10.8% |