| | Lyme, CT | Groton, CT | United States |
| Population | 2,430 | 38,686 | 329,725,481 |
| Female Population | 48.5% | 44.7% | 50.5% |
| Male Population | 51.5% | 55.3% | 49.5% |
| Median Age | 52.5 | 34.2 | 38.4 |
| space3 | | | |
| Population - 2010 | 2,400 | 40,094 | 309,327,143 |
| Population - 2000 | 2,016 | 39,907 | 285,036,114 |
| Population - 1990 | 1,949 | 45,144 | 251,960,433 |
| Pop. 2000 to Now | 14.3% | -4.1% | 15.6% |
| Pop. 1990 to Now | 18.2% | -15.3% | 30.8% |
| space4 | | | |
| Population Density | 76.4 | 1,246.7 | 93.4 |
| Land Area | 31.8 | 31.0 | 3,531,905.4 |
| Water Area | 2.7 | 14.3 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Lyme, CT | Groton, CT | United States |
| Age 0 to 4 | 3.3% | 6.0% | 5.9% |
| Age 5 to 9 | 3.8% | 4.4% | 6.1% |
| Age 10 to 14 | 4.5% | 5.6% | 6.6% |
| Age 15 to 17 | 2.4% | 3.0% | 3.9% |
| Age 18 to 20 | 3.6% | 5.6% | 4.0% |
| Age 21 to 24 | 7.4% | 9.3% | 5.2% |
| Age 25 to 34 | 8.3% | 17.3% | 13.8% |
| Age 35 to 44 | 11.3% | 10.0% | 12.9% |
| Age 45 to 54 | 10.3% | 10.4% | 12.6% |
| Age 55 to 59 | 11.1% | 5.9% | 6.7% |
| Age 60 to 64 | 8.4% | 5.5% | 6.3% |
| Age 65 to 74 | 16.4% | 8.9% | 9.6% |
| Age 75 to 84 | 7.5% | 4.9% | 4.5% |
| Age 85 and over | 1.6% | 3.3% | 1.9% |
| space1 | | | |
| Race | | | |
| | Lyme, CT | Groton, CT | United States |
| White | 91.6% | 67.0% | 59.4% |
| Black | 3.2% | 5.9% | 12.2% |
| Asian | 0.3% | 7.0% | 5.6% |
| Native American | 0.0% | 0.4% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 1.2% | 0.3% | 0.4% |
| Two or More Races | 2.9% | 6.2% | 3.2% |
| Hispanic | 0.8% | 13.1% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Lyme, CT | Groton, CT | United States |
| Married Population | 57.1% | 46.3% | 49.8% |
| Currently Married | 56.8% | 45.9% | 48.0% |
| Married but Separated | 0.4% | 0.4% | 1.8% |
| Single Population | 42.9% | 53.7% | 50.2% |
| Never Married | 27.0% | 37.2% | 33.8% |
| Divorced | 11.6% | 11.6% | 10.8% |
| Widowed | 4.2% | 5.0% | 5.6% |
| space5 | | | |
| Household Size | 2.55 | 2.23 | 2.60 |
| Households | 951 | 16,043 | 124,010,992 |
| Family Households | 710 | 9,685 | 80,755,759 |
| Married couple, w/children | 18.3% | 27.4% | 30.5% |
| Married couple, no children | 61.7% | 42.6% | 42.9% |
| Non Family Households | 241 | 6,358 | 43,255,233 |
| Single householder, w/children | 12.3% | 18.2% | 15.8% |
| Single householder, no children | 7.7% | 11.8% | 10.8% |