| | Millbrook, NY | Millerton, NY | United States |
| Population | 1,364 | 871 | 329,725,481 |
| Female Population | 53.0% | 54.3% | 50.5% |
| Male Population | 47.0% | 45.7% | 49.5% |
| Median Age | 56 | 45.2 | 38.4 |
| space3 | | | |
| Population - 2010 | 1,453 | 956 | 309,327,143 |
| Population - 2000 | 1,429 | 925 | 285,036,114 |
| Population - 1990 | 1,339 | 884 | 251,960,433 |
| Pop. 2000 to Now | -2.8% | -1.5% | 15.6% |
| Pop. 1990 to Now | 3.7% | 3.1% | 30.8% |
| space4 | | | |
| Population Density | 733.3 | 1,454.1 | 93.4 |
| Land Area | 1.9 | 0.6 | 3,531,905.4 |
| Water Area | 0.1 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Millbrook, NY | Millerton, NY | United States |
| Age 0 to 4 | 4.5% | 8.2% | 5.9% |
| Age 5 to 9 | 0.3% | 3.2% | 6.1% |
| Age 10 to 14 | 1.4% | 5.6% | 6.6% |
| Age 15 to 17 | 5.4% | 4.7% | 3.9% |
| Age 18 to 20 | 1.2% | 2.2% | 4.0% |
| Age 21 to 24 | 3.0% | 4.2% | 5.2% |
| Age 25 to 34 | 9.8% | 13.8% | 13.8% |
| Age 35 to 44 | 10.0% | 7.2% | 12.9% |
| Age 45 to 54 | 13.0% | 15.7% | 12.6% |
| Age 55 to 59 | 9.5% | 8.7% | 6.7% |
| Age 60 to 64 | 10.3% | 6.4% | 6.3% |
| Age 65 to 74 | 11.4% | 13.1% | 9.6% |
| Age 75 to 84 | 14.9% | 6.2% | 4.5% |
| Age 85 and over | 5.3% | 0.7% | 1.9% |
| space1 | | | |
| Race | | | |
| | Millbrook, NY | Millerton, NY | United States |
| White | 85.3% | 69.1% | 59.4% |
| Black | 2.9% | 2.6% | 12.2% |
| Asian | 5.5% | 7.5% | 5.6% |
| Native American | 0.3% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 1.0% | 6.3% | 3.2% |
| Hispanic | 5.1% | 14.5% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Millbrook, NY | Millerton, NY | United States |
| Married Population | 48.9% | 54.2% | 49.8% |
| Currently Married | 46.9% | 50.5% | 48.0% |
| Married but Separated | 2.0% | 3.7% | 1.8% |
| Single Population | 51.1% | 45.8% | 50.2% |
| Never Married | 30.0% | 33.3% | 33.8% |
| Divorced | 12.4% | 7.3% | 10.8% |
| Widowed | 8.6% | 5.1% | 5.6% |
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| Household Size | 1.85 | 2.40 | 2.60 |
| Households | 733 | 361 | 124,010,992 |
| Family Households | 321 | 209 | 80,755,759 |
| Married couple, w/children | 16.5% | 25.8% | 30.5% |
| Married couple, no children | 62.0% | 46.9% | 42.9% |
| Non Family Households | 412 | 152 | 43,255,233 |
| Single householder, w/children | 10.9% | 21.5% | 15.8% |
| Single householder, no children | 10.6% | 5.7% | 10.8% |