| | Heflin, AL | Marion, AL | United States |
| Population | 3,416 | 3,273 | 329,725,481 |
| Female Population | 55.7% | 59.3% | 50.5% |
| Male Population | 44.3% | 40.7% | 49.5% |
| Median Age | 42 | 30.6 | 38.4 |
| space3 | | | |
| Population - 2010 | 3,493 | 3,675 | 309,327,143 |
| Population - 2000 | 3,002 | 3,511 | 285,036,114 |
| Population - 1990 | 2,906 | 4,211 | 251,960,433 |
| Pop. 2000 to Now | 13.5% | -13.2% | 15.6% |
| Pop. 1990 to Now | 17.3% | -27.6% | 30.8% |
| space4 | | | |
| Population Density | 212.4 | 309.8 | 93.4 |
| Land Area | 16.1 | 10.6 | 3,531,905.4 |
| Water Area | 0.2 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Heflin, AL | Marion, AL | United States |
| Age 0 to 4 | 6.4% | 4.6% | 5.9% |
| Age 5 to 9 | 5.0% | 7.3% | 6.1% |
| Age 10 to 14 | 7.9% | 7.1% | 6.6% |
| Age 15 to 17 | 3.6% | 2.5% | 3.9% |
| Age 18 to 20 | 2.1% | 14.6% | 4.0% |
| Age 21 to 24 | 2.3% | 6.8% | 5.2% |
| Age 25 to 34 | 9.3% | 10.8% | 13.8% |
| Age 35 to 44 | 18.4% | 7.4% | 12.9% |
| Age 45 to 54 | 9.1% | 7.8% | 12.6% |
| Age 55 to 59 | 5.6% | 6.4% | 6.7% |
| Age 60 to 64 | 9.0% | 1.7% | 6.3% |
| Age 65 to 74 | 14.9% | 16.5% | 9.6% |
| Age 75 to 84 | 3.4% | 4.5% | 4.5% |
| Age 85 and over | 3.0% | 2.1% | 1.9% |
| space1 | | | |
| Race | | | |
| | Heflin, AL | Marion, AL | United States |
| White | 87.6% | 35.9% | 59.4% |
| Black | 6.6% | 60.9% | 12.2% |
| Asian | 0.0% | 0.2% | 5.6% |
| Native American | 0.4% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 3.9% | 0.2% | 3.2% |
| Hispanic | 1.5% | 2.7% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Heflin, AL | Marion, AL | United States |
| Married Population | 44.9% | 23.4% | 49.8% |
| Currently Married | 42.0% | 22.7% | 48.0% |
| Married but Separated | 2.9% | 0.6% | 1.8% |
| Single Population | 55.1% | 76.6% | 50.2% |
| Never Married | 23.1% | 53.7% | 33.8% |
| Divorced | 18.6% | 7.2% | 10.8% |
| Widowed | 13.4% | 15.8% | 5.6% |
| space5 | | | |
| Household Size | 2.50 | 3.11 | 2.60 |
| Households | 1,308 | 794 | 124,010,992 |
| Family Households | 793 | 475 | 80,755,759 |
| Married couple, w/children | 24.2% | 13.3% | 30.5% |
| Married couple, no children | 35.1% | 22.3% | 42.9% |
| Non Family Households | 515 | 319 | 43,255,233 |
| Single householder, w/children | 17.2% | 29.3% | 15.8% |
| Single householder, no children | 23.6% | 35.2% | 10.8% |