| | Atlanta, GA | Libby, MT | United States |
| Population | 492,204 | 2,745 | 329,725,481 |
| Female Population | 51.1% | 50.1% | 50.5% |
| Male Population | 49.0% | 49.9% | 49.5% |
| Median Age | 33.4 | 50.1 | 38.4 |
| space3 | | | |
| Population - 2010 | 429,414 | 2,631 | 309,327,143 |
| Population - 2000 | 416,474 | 2,626 | 285,036,114 |
| Population - 1990 | 394,017 | 2,532 | 251,960,433 |
| Pop. 2000 to Now | 23.1% | 8.3% | 15.6% |
| Pop. 1990 to Now | 30.1% | 12.4% | 30.8% |
| space4 | | | |
| Population Density | 3,630.3 | 1,465.6 | 93.4 |
| Land Area | 135.6 | 1.9 | 3,531,905.4 |
| Water Area | 1.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Atlanta, GA | Libby, MT | United States |
| Age 0 to 4 | 5.3% | 4.9% | 5.9% |
| Age 5 to 9 | 5.2% | 3.1% | 6.1% |
| Age 10 to 14 | 4.3% | 2.8% | 6.6% |
| Age 15 to 17 | 2.5% | 6.6% | 3.9% |
| Age 18 to 20 | 6.2% | 4.4% | 4.0% |
| Age 21 to 24 | 7.6% | 3.9% | 5.2% |
| Age 25 to 34 | 21.6% | 8.2% | 13.8% |
| Age 35 to 44 | 14.2% | 10.5% | 12.9% |
| Age 45 to 54 | 11.4% | 14.6% | 12.6% |
| Age 55 to 59 | 5.1% | 6.7% | 6.7% |
| Age 60 to 64 | 5.0% | 8.8% | 6.3% |
| Age 65 to 74 | 7.0% | 9.3% | 9.6% |
| Age 75 to 84 | 3.2% | 10.9% | 4.5% |
| Age 85 and over | 1.4% | 5.2% | 1.9% |
| space1 | | | |
| Race | | | |
| | Atlanta, GA | Libby, MT | United States |
| White | 39.1% | 83.7% | 59.4% |
| Black | 47.7% | 0.4% | 12.2% |
| Asian | 5.0% | 0.5% | 5.6% |
| Native American | 0.2% | 4.5% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.4% | 0.0% | 0.4% |
| Two or More Races | 2.6% | 4.8% | 3.2% |
| Hispanic | 5.0% | 6.1% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Atlanta, GA | Libby, MT | United States |
| Married Population | 30.8% | 45.0% | 49.8% |
| Currently Married | 29.0% | 42.2% | 48.0% |
| Married but Separated | 1.8% | 2.8% | 1.8% |
| Single Population | 69.2% | 55.0% | 50.2% |
| Never Married | 55.1% | 31.9% | 33.8% |
| Divorced | 10.1% | 12.0% | 10.8% |
| Widowed | 4.0% | 11.1% | 5.6% |
| space5 | | | |
| Household Size | 2.06 | 1.94 | 2.60 |
| Households | 221,171 | 1,354 | 124,010,992 |
| Family Households | 92,650 | 665 | 80,755,759 |
| Married couple, w/children | 21.8% | 21.2% | 30.5% |
| Married couple, no children | 37.9% | 60.9% | 42.9% |
| Non Family Households | 128,521 | 689 | 43,255,233 |
| Single householder, w/children | 23.8% | 16.2% | 15.8% |
| Single householder, no children | 16.4% | 1.7% | 10.8% |