| | South St. Paul, MN | Springfield, VA | United States |
| Population | 20,637 | 31,769 | 329,725,481 |
| Female Population | 51.1% | 49.8% | 50.5% |
| Male Population | 48.9% | 50.2% | 49.5% |
| Median Age | 36.3 | 41 | 38.4 |
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| Population - 2010 | 20,129 | 30,548 | 309,327,143 |
| Population - 2000 | 20,167 | 30,417 | 285,036,114 |
| Population - 1990 | 20,236 | 23,706 | 251,960,433 |
| Pop. 2000 to Now | -1.2% | 1.3% | 15.6% |
| Pop. 1990 to Now | -1.6% | 30.0% | 30.8% |
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| Population Density | 3,670.1 | 4,046.0 | 93.4 |
| Land Area | 5.6 | 7.9 | 3,531,905.4 |
| Water Area | 0.5 | 0.1 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | South St. Paul, MN | Springfield, VA | United States |
| Age 0 to 4 | 5.5% | 6.0% | 5.9% |
| Age 5 to 9 | 6.2% | 5.0% | 6.1% |
| Age 10 to 14 | 7.4% | 4.9% | 6.6% |
| Age 15 to 17 | 4.0% | 3.5% | 3.9% |
| Age 18 to 20 | 3.4% | 3.2% | 4.0% |
| Age 21 to 24 | 6.1% | 6.3% | 5.2% |
| Age 25 to 34 | 15.8% | 12.6% | 13.8% |
| Age 35 to 44 | 13.3% | 13.0% | 12.9% |
| Age 45 to 54 | 11.7% | 12.8% | 12.6% |
| Age 55 to 59 | 6.1% | 7.3% | 6.7% |
| Age 60 to 64 | 6.9% | 5.3% | 6.3% |
| Age 65 to 74 | 7.8% | 10.3% | 9.6% |
| Age 75 to 84 | 3.8% | 5.6% | 4.5% |
| Age 85 and over | 2.1% | 4.1% | 1.9% |
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| Race | | | |
| | South St. Paul, MN | Springfield, VA | United States |
| White | 72.3% | 37.4% | 59.4% |
| Black | 3.9% | 10.5% | 12.2% |
| Asian | 2.4% | 29.4% | 5.6% |
| Native American | 0.3% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.5% | 0.4% |
| Two or More Races | 6.0% | 2.9% | 3.2% |
| Hispanic | 15.1% | 19.1% | 18.4% |
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| Marriage & Family | | | |
| | South St. Paul, MN | Springfield, VA | United States |
| Married Population | 43.9% | 50.9% | 49.8% |
| Currently Married | 42.8% | 49.2% | 48.0% |
| Married but Separated | 1.1% | 1.6% | 1.8% |
| Single Population | 56.1% | 49.1% | 50.2% |
| Never Married | 36.2% | 33.5% | 33.8% |
| Divorced | 14.3% | 6.9% | 10.8% |
| Widowed | 5.5% | 8.7% | 5.6% |
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| Household Size | 2.46 | 2.95 | 2.60 |
| Households | 8,329 | 10,697 | 124,010,992 |
| Family Households | 5,052 | 7,247 | 80,755,759 |
| Married couple, w/children | 25.2% | 31.4% | 30.5% |
| Married couple, no children | 42.0% | 44.3% | 42.9% |
| Non Family Households | 3,277 | 3,450 | 43,255,233 |
| Single householder, w/children | 23.6% | 11.0% | 15.8% |
| Single householder, no children | 9.2% | 13.3% | 10.8% |