| | Westerly, RI | Oneonta, NY | United States |
| Population | 23,352 | 12,764 | 329,725,481 |
| Female Population | 49.6% | 52.3% | 50.5% |
| Male Population | 50.4% | 47.7% | 49.5% |
| Median Age | 50 | 21.9 | 38.4 |
| space3 | | | |
| Population - 2010 | 22,770 | 13,945 | 309,327,143 |
| Population - 2000 | 22,966 | 13,292 | 285,036,114 |
| Population - 1990 | 21,605 | 13,954 | 251,960,433 |
| Pop. 2000 to Now | -2.8% | 3.0% | 15.6% |
| Pop. 1990 to Now | 3.4% | -1.9% | 30.8% |
| space4 | | | |
| Population Density | 790.7 | 2,926.9 | 93.4 |
| Land Area | 29.5 | 4.4 | 3,531,905.4 |
| Water Area | 45.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Westerly, RI | Oneonta, NY | United States |
| Age 0 to 4 | 3.1% | 3.4% | 5.9% |
| Age 5 to 9 | 3.5% | 1.6% | 6.1% |
| Age 10 to 14 | 4.4% | 3.2% | 6.6% |
| Age 15 to 17 | 3.3% | 1.4% | 3.9% |
| Age 18 to 20 | 3.8% | 32.5% | 4.0% |
| Age 21 to 24 | 5.7% | 13.1% | 5.2% |
| Age 25 to 34 | 11.7% | 8.9% | 13.8% |
| Age 35 to 44 | 8.6% | 7.1% | 12.9% |
| Age 45 to 54 | 15.0% | 7.5% | 12.6% |
| Age 55 to 59 | 9.3% | 3.3% | 6.7% |
| Age 60 to 64 | 8.6% | 4.2% | 6.3% |
| Age 65 to 74 | 13.8% | 7.7% | 9.6% |
| Age 75 to 84 | 6.2% | 4.0% | 4.5% |
| Age 85 and over | 3.2% | 2.1% | 1.9% |
| space1 | | | |
| Race | | | |
| | Westerly, RI | Oneonta, NY | United States |
| White | 90.5% | 81.3% | 59.4% |
| Black | 0.9% | 5.0% | 12.2% |
| Asian | 2.2% | 2.7% | 5.6% |
| Native American | 0.1% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.7% | 0.4% | 0.4% |
| Two or More Races | 2.2% | 2.9% | 3.2% |
| Hispanic | 3.4% | 7.6% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Westerly, RI | Oneonta, NY | United States |
| Married Population | 51.0% | 23.3% | 49.8% |
| Currently Married | 50.2% | 22.2% | 48.0% |
| Married but Separated | 0.8% | 1.1% | 1.8% |
| Single Population | 49.0% | 76.7% | 50.2% |
| Never Married | 29.7% | 64.6% | 33.8% |
| Divorced | 12.8% | 8.1% | 10.8% |
| Widowed | 6.5% | 4.0% | 5.6% |
| space5 | | | |
| Household Size | 2.20 | 2.06 | 2.60 |
| Households | 10,507 | 3,935 | 124,010,992 |
| Family Households | 6,610 | 1,984 | 80,755,759 |
| Married couple, w/children | 20.1% | 21.1% | 30.5% |
| Married couple, no children | 56.8% | 44.2% | 42.9% |
| Non Family Households | 3,897 | 1,951 | 43,255,233 |
| Single householder, w/children | 11.3% | 21.0% | 15.8% |
| Single householder, no children | 11.8% | 13.8% | 10.8% |