| | Union, CT | Thompson, CT | United States |
| Population | 932 | 9,213 | 329,725,481 |
| Female Population | 57.0% | 51.1% | 50.5% |
| Male Population | 43.0% | 48.9% | 49.5% |
| Median Age | 50.4 | 50.3 | 38.4 |
| space3 | | | |
| Population - 2010 | 853 | 9,489 | 309,327,143 |
| Population - 2000 | 693 | 8,878 | 285,036,114 |
| Population - 1990 | 612 | 8,668 | 251,960,433 |
| Pop. 2000 to Now | 21.8% | 5.6% | 15.6% |
| Pop. 1990 to Now | 37.9% | 8.1% | 30.8% |
| space4 | | | |
| Population Density | 32.4 | 196.4 | 93.4 |
| Land Area | 28.8 | 46.9 | 3,531,905.4 |
| Water Area | 1.0 | 1.8 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Union, CT | Thompson, CT | United States |
| Age 0 to 4 | 2.6% | 4.4% | 5.9% |
| Age 5 to 9 | 4.4% | 4.2% | 6.1% |
| Age 10 to 14 | 4.8% | 4.5% | 6.6% |
| Age 15 to 17 | 3.4% | 3.5% | 3.9% |
| Age 18 to 20 | 3.5% | 2.3% | 4.0% |
| Age 21 to 24 | 0.8% | 3.1% | 5.2% |
| Age 25 to 34 | 7.9% | 12.9% | 13.8% |
| Age 35 to 44 | 11.4% | 11.8% | 12.9% |
| Age 45 to 54 | 19.9% | 12.2% | 12.6% |
| Age 55 to 59 | 11.1% | 11.1% | 6.7% |
| Age 60 to 64 | 7.3% | 10.3% | 6.3% |
| Age 65 to 74 | 13.6% | 14.2% | 9.6% |
| Age 75 to 84 | 8.6% | 2.6% | 4.5% |
| Age 85 and over | 0.8% | 3.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Union, CT | Thompson, CT | United States |
| White | 90.8% | 90.4% | 59.4% |
| Black | 0.0% | 0.0% | 12.2% |
| Asian | 1.2% | 0.9% | 5.6% |
| Native American | 0.1% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.3% | 0.0% | 0.2% |
| Other | 0.5% | 0.4% | 0.4% |
| Two or More Races | 1.4% | 3.8% | 3.2% |
| Hispanic | 5.7% | 4.5% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Union, CT | Thompson, CT | United States |
| Married Population | 71.3% | 50.4% | 49.8% |
| Currently Married | 71.0% | 49.7% | 48.0% |
| Married but Separated | 0.2% | 0.7% | 1.8% |
| Single Population | 28.7% | 49.6% | 50.2% |
| Never Married | 14.5% | 28.5% | 33.8% |
| Divorced | 10.9% | 15.0% | 10.8% |
| Widowed | 3.3% | 6.1% | 5.6% |
| space5 | | | |
| Household Size | 2.26 | 2.40 | 2.60 |
| Households | 413 | 3,802 | 124,010,992 |
| Family Households | 340 | 2,438 | 80,755,759 |
| Married couple, w/children | 15.0% | 24.7% | 30.5% |
| Married couple, no children | 71.8% | 53.2% | 42.9% |
| Non Family Households | 73 | 1,364 | 43,255,233 |
| Single householder, w/children | 6.2% | 15.0% | 15.8% |
| Single householder, no children | 7.1% | 7.1% | 10.8% |