| | Union, MS | Fayette, AL | United States |
| Population | 2,750 | 4,271 | 329,725,481 |
| Female Population | 51.2% | 51.4% | 50.5% |
| Male Population | 48.8% | 48.6% | 49.5% |
| Median Age | 34.6 | 47.5 | 38.4 |
| space3 | | | |
| Population - 2010 | 1,983 | 4,619 | 309,327,143 |
| Population - 2000 | 2,021 | 4,922 | 285,036,114 |
| Population - 1990 | 1,875 | 4,909 | 251,960,433 |
| Pop. 2000 to Now | -7.2% | -13.7% | 15.6% |
| Pop. 1990 to Now | 0.1% | -13.4% | 30.8% |
| space4 | | | |
| Population Density | 802.7 | 499.5 | 93.4 |
| Land Area | 3.4 | 8.6 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Union, MS | Fayette, AL | United States |
| Age 0 to 4 | 10.5% | 8.1% | 5.9% |
| Age 5 to 9 | 7.9% | 7.0% | 6.1% |
| Age 10 to 14 | 9.6% | 2.2% | 6.6% |
| Age 15 to 17 | 5.0% | 2.4% | 3.9% |
| Age 18 to 20 | 2.9% | 3.1% | 4.0% |
| Age 21 to 24 | 3.7% | 3.7% | 5.2% |
| Age 25 to 34 | 10.9% | 13.9% | 13.8% |
| Age 35 to 44 | 10.3% | 8.2% | 12.9% |
| Age 45 to 54 | 9.7% | 11.9% | 12.6% |
| Age 55 to 59 | 7.6% | 6.3% | 6.7% |
| Age 60 to 64 | 5.7% | 9.9% | 6.3% |
| Age 65 to 74 | 5.3% | 10.7% | 9.6% |
| Age 75 to 84 | 8.3% | 7.1% | 4.5% |
| Age 85 and over | 2.6% | 5.4% | 1.9% |
| space1 | | | |
| Race | | | |
| | Union, MS | Fayette, AL | United States |
| White | 44.5% | 64.2% | 59.4% |
| Black | 48.9% | 30.2% | 12.2% |
| Asian | 0.0% | 1.2% | 5.6% |
| Native American | 0.8% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.2% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 5.5% | 3.1% | 3.2% |
| Hispanic | 0.3% | 1.1% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Union, MS | Fayette, AL | United States |
| Married Population | 37.0% | 45.9% | 49.8% |
| Currently Married | 34.9% | 43.9% | 48.0% |
| Married but Separated | 2.1% | 2.0% | 1.8% |
| Single Population | 63.0% | 54.1% | 50.2% |
| Never Married | 41.6% | 27.4% | 33.8% |
| Divorced | 7.9% | 14.4% | 10.8% |
| Widowed | 13.5% | 12.3% | 5.6% |
| space5 | | | |
| Household Size | 3.16 | 2.42 | 2.60 |
| Households | 856 | 1,672 | 124,010,992 |
| Family Households | 519 | 962 | 80,755,759 |
| Married couple, w/children | 24.7% | 17.6% | 30.5% |
| Married couple, no children | 36.4% | 54.9% | 42.9% |
| Non Family Households | 337 | 710 | 43,255,233 |
| Single householder, w/children | 31.2% | 20.4% | 15.8% |
| Single householder, no children | 7.7% | 7.2% | 10.8% |