| | Keystone, CO | Mendon, VT | United States |
| Population | 611 | 1,055 | 329,725,481 |
| Female Population | 63.2% | 50.5% | 50.5% |
| Male Population | 36.8% | 49.5% | 49.5% |
| Median Age | 34 | 53.2 | 38.4 |
| space3 | | | |
| Population - 2010 | 765 | 1,064 | 309,327,143 |
| Population - 2000 | 825 | 1,028 | 285,036,114 |
| Population - 1990 | 466 | 1,049 | 251,960,433 |
| Pop. 2000 to Now | 46.6% | -1.3% | 15.6% |
| Pop. 1990 to Now | 159.4% | -3.2% | 30.8% |
| space4 | | | |
| Population Density | 14.8 | 27.7 | 93.4 |
| Land Area | 41.4 | 38.1 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Keystone, CO | Mendon, VT | United States |
| Age 0 to 4 | 0.0% | 1.7% | 5.9% |
| Age 5 to 9 | 0.0% | 3.7% | 6.1% |
| Age 10 to 14 | 0.0% | 11.8% | 6.6% |
| Age 15 to 17 | 0.0% | 2.7% | 3.9% |
| Age 18 to 20 | 2.5% | 4.6% | 4.0% |
| Age 21 to 24 | 30.4% | 3.4% | 5.2% |
| Age 25 to 34 | 18.8% | 4.5% | 13.8% |
| Age 35 to 44 | 18.8% | 9.3% | 12.9% |
| Age 45 to 54 | 11.3% | 11.8% | 12.6% |
| Age 55 to 59 | 0.0% | 11.0% | 6.7% |
| Age 60 to 64 | 2.9% | 12.3% | 6.3% |
| Age 65 to 74 | 5.4% | 15.2% | 9.6% |
| Age 75 to 84 | 9.8% | 7.2% | 4.5% |
| Age 85 and over | 0.0% | 0.8% | 1.9% |
| space1 | | | |
| Race | | | |
| | Keystone, CO | Mendon, VT | United States |
| White | 43.9% | 96.1% | 59.4% |
| Black | 3.3% | 0.5% | 12.2% |
| Asian | 0.0% | 1.1% | 5.6% |
| Native American | 6.7% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 7.0% | 2.3% | 3.2% |
| Hispanic | 39.1% | 0.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Keystone, CO | Mendon, VT | United States |
| Married Population | 18.2% | 58.6% | 49.8% |
| Currently Married | 13.9% | 58.2% | 48.0% |
| Married but Separated | 4.3% | 0.5% | 1.8% |
| Single Population | 81.8% | 41.4% | 50.2% |
| Never Married | 54.0% | 24.2% | 33.8% |
| Divorced | 27.8% | 10.4% | 10.8% |
| Widowed | 0.0% | 6.8% | 5.6% |
| space5 | | | |
| Household Size | 1.37 | 2.64 | 2.60 |
| Households | 327 | 399 | 124,010,992 |
| Family Households | 29 | 269 | 80,755,759 |
| Married couple, w/children | 0.0% | 23.4% | 30.5% |
| Married couple, no children | 100.0% | 60.2% | 42.9% |
| Non Family Households | 298 | 130 | 43,255,233 |
| Single householder, w/children | 0.0% | 8.6% | 15.8% |
| Single householder, no children | 0.0% | 7.8% | 10.8% |