| | Grundy, VA | Louisville, CO | United States |
| Population | 1,112 | 21,091 | 329,725,481 |
| Female Population | 53.1% | 49.4% | 50.5% |
| Male Population | 46.9% | 50.6% | 49.5% |
| Median Age | 47.2 | 42.5 | 38.4 |
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| Population - 2010 | 1,010 | 18,412 | 309,327,143 |
| Population - 2000 | 1,105 | 18,937 | 285,036,114 |
| Population - 1990 | 1,305 | 12,361 | 251,960,433 |
| Pop. 2000 to Now | -20.1% | 0.7% | 15.6% |
| Pop. 1990 to Now | -32.3% | 54.2% | 30.8% |
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| Population Density | 223.0 | 2,644.0 | 93.4 |
| Land Area | 5.0 | 8.0 | 3,531,905.4 |
| Water Area | 0.1 | 0.1 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Grundy, VA | Louisville, CO | United States |
| Age 0 to 4 | 2.5% | 4.5% | 5.9% |
| Age 5 to 9 | 2.2% | 6.8% | 6.1% |
| Age 10 to 14 | 4.7% | 8.0% | 6.6% |
| Age 15 to 17 | 11.4% | 4.3% | 3.9% |
| Age 18 to 20 | 3.9% | 2.8% | 4.0% |
| Age 21 to 24 | 1.4% | 3.4% | 5.2% |
| Age 25 to 34 | 13.0% | 11.2% | 13.8% |
| Age 35 to 44 | 6.2% | 13.0% | 12.9% |
| Age 45 to 54 | 13.6% | 15.1% | 12.6% |
| Age 55 to 59 | 5.8% | 8.6% | 6.7% |
| Age 60 to 64 | 11.4% | 8.0% | 6.3% |
| Age 65 to 74 | 4.9% | 9.0% | 9.6% |
| Age 75 to 84 | 7.0% | 3.0% | 4.5% |
| Age 85 and over | 12.1% | 2.3% | 1.9% |
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| Race | | | |
| | Grundy, VA | Louisville, CO | United States |
| White | 75.0% | 82.3% | 59.4% |
| Black | 13.9% | 0.6% | 12.2% |
| Asian | 0.0% | 4.1% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 4.1% | 0.1% | 0.4% |
| Two or More Races | 5.8% | 4.0% | 3.2% |
| Hispanic | 1.1% | 8.8% | 18.4% |
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| Marriage & Family | | | |
| | Grundy, VA | Louisville, CO | United States |
| Married Population | 41.0% | 56.9% | 49.8% |
| Currently Married | 38.5% | 56.6% | 48.0% |
| Married but Separated | 2.5% | 0.3% | 1.8% |
| Single Population | 59.0% | 43.1% | 50.2% |
| Never Married | 28.1% | 27.8% | 33.8% |
| Divorced | 7.8% | 10.9% | 10.8% |
| Widowed | 23.1% | 4.4% | 5.6% |
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| Household Size | 2.20 | 2.50 | 2.60 |
| Households | 425 | 8,400 | 124,010,992 |
| Family Households | 176 | 5,519 | 80,755,759 |
| Married couple, w/children | 5.7% | 38.7% | 30.5% |
| Married couple, no children | 73.9% | 43.2% | 42.9% |
| Non Family Households | 249 | 2,881 | 43,255,233 |
| Single householder, w/children | 17.0% | 12.2% | 15.8% |
| Single householder, no children | 3.4% | 5.9% | 10.8% |