| | Deerfield, IL | Mystic, CT | United States |
| Population | 19,228 | 4,354 | 329,725,481 |
| Female Population | 50.4% | 49.4% | 50.5% |
| Male Population | 49.6% | 50.6% | 49.5% |
| Median Age | 44.3 | 54.4 | 38.4 |
| space3 | | | |
| Population - 2010 | 18,245 | 3,959 | 309,327,143 |
| Population - 2000 | 18,420 | 4,001 | 285,036,114 |
| Population - 1990 | 17,327 | 2,618 | 251,960,433 |
| Pop. 2000 to Now | 0.6% | 4.8% | 15.6% |
| Pop. 1990 to Now | 7.0% | 60.1% | 30.8% |
| space4 | | | |
| Population Density | 3,477.0 | 1,298.9 | 93.4 |
| Land Area | 5.5 | 3.4 | 3,531,905.4 |
| Water Area | 0.0 | 0.4 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Deerfield, IL | Mystic, CT | United States |
| Age 0 to 4 | 3.8% | 3.4% | 5.9% |
| Age 5 to 9 | 7.8% | 6.0% | 6.1% |
| Age 10 to 14 | 8.1% | 1.4% | 6.6% |
| Age 15 to 17 | 4.8% | 2.2% | 3.9% |
| Age 18 to 20 | 2.6% | 1.9% | 4.0% |
| Age 21 to 24 | 3.7% | 2.6% | 5.2% |
| Age 25 to 34 | 7.9% | 6.0% | 13.8% |
| Age 35 to 44 | 12.6% | 9.9% | 12.9% |
| Age 45 to 54 | 15.0% | 17.8% | 12.6% |
| Age 55 to 59 | 8.2% | 5.7% | 6.7% |
| Age 60 to 64 | 8.3% | 8.1% | 6.3% |
| Age 65 to 74 | 8.7% | 11.8% | 9.6% |
| Age 75 to 84 | 4.9% | 17.7% | 4.5% |
| Age 85 and over | 3.5% | 5.5% | 1.9% |
| space1 | | | |
| Race | | | |
| | Deerfield, IL | Mystic, CT | United States |
| White | 88.2% | 80.2% | 59.4% |
| Black | 0.4% | 1.6% | 12.2% |
| Asian | 5.2% | 2.0% | 5.6% |
| Native American | 0.0% | 1.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.1% | 0.6% | 0.4% |
| Two or More Races | 2.0% | 12.9% | 3.2% |
| Hispanic | 4.1% | 1.7% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Deerfield, IL | Mystic, CT | United States |
| Married Population | 67.1% | 60.2% | 49.8% |
| Currently Married | 67.0% | 60.1% | 48.0% |
| Married but Separated | 0.1% | 0.1% | 1.8% |
| Single Population | 32.9% | 39.8% | 50.2% |
| Never Married | 20.1% | 18.2% | 33.8% |
| Divorced | 7.6% | 12.8% | 10.8% |
| Widowed | 5.2% | 8.8% | 5.6% |
| space5 | | | |
| Household Size | 2.56 | 1.98 | 2.60 |
| Households | 7,475 | 2,067 | 124,010,992 |
| Family Households | 5,634 | 1,188 | 80,755,759 |
| Married couple, w/children | 38.0% | 29.9% | 30.5% |
| Married couple, no children | 52.8% | 62.3% | 42.9% |
| Non Family Households | 1,841 | 879 | 43,255,233 |
| Single householder, w/children | 6.6% | 2.2% | 15.8% |
| Single householder, no children | 2.6% | 5.6% | 10.8% |