| | Jamestown, NY | Dunkirk, NY | United States |
| Population | 28,818 | 12,651 | 329,725,481 |
| Female Population | 50.9% | 49.0% | 50.5% |
| Male Population | 49.2% | 51.0% | 49.5% |
| Median Age | 36.8 | 42.4 | 38.4 |
| space3 | | | |
| Population - 2010 | 31,079 | 12,527 | 309,327,143 |
| Population - 2000 | 31,730 | 13,131 | 285,036,114 |
| Population - 1990 | 34,681 | 13,989 | 251,960,433 |
| Pop. 2000 to Now | -9.0% | -10.9% | 15.6% |
| Pop. 1990 to Now | -16.8% | -16.4% | 30.8% |
| space4 | | | |
| Population Density | 3,225.7 | 2,808.2 | 93.4 |
| Land Area | 8.9 | 4.5 | 3,531,905.4 |
| Water Area | 0.1 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Jamestown, NY | Dunkirk, NY | United States |
| Age 0 to 4 | 7.4% | 5.3% | 5.9% |
| Age 5 to 9 | 6.9% | 6.0% | 6.1% |
| Age 10 to 14 | 6.3% | 5.0% | 6.6% |
| Age 15 to 17 | 3.6% | 2.7% | 3.9% |
| Age 18 to 20 | 3.4% | 3.3% | 4.0% |
| Age 21 to 24 | 5.1% | 6.0% | 5.2% |
| Age 25 to 34 | 15.0% | 12.8% | 13.8% |
| Age 35 to 44 | 10.9% | 11.7% | 12.9% |
| Age 45 to 54 | 11.6% | 11.9% | 12.6% |
| Age 55 to 59 | 6.5% | 7.6% | 6.7% |
| Age 60 to 64 | 6.7% | 9.7% | 6.3% |
| Age 65 to 74 | 9.1% | 11.6% | 9.6% |
| Age 75 to 84 | 4.4% | 4.7% | 4.5% |
| Age 85 and over | 3.1% | 1.6% | 1.9% |
| space1 | | | |
| Race | | | |
| | Jamestown, NY | Dunkirk, NY | United States |
| White | 82.3% | 61.9% | 59.4% |
| Black | 2.5% | 6.9% | 12.2% |
| Asian | 0.2% | 0.1% | 5.6% |
| Native American | 0.2% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.1% | 0.0% | 0.4% |
| Two or More Races | 4.1% | 2.6% | 3.2% |
| Hispanic | 10.6% | 28.2% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Jamestown, NY | Dunkirk, NY | United States |
| Married Population | 36.4% | 37.8% | 49.8% |
| Currently Married | 33.5% | 36.3% | 48.0% |
| Married but Separated | 2.9% | 1.6% | 1.8% |
| Single Population | 63.6% | 62.2% | 50.2% |
| Never Married | 42.2% | 41.5% | 33.8% |
| Divorced | 14.7% | 13.6% | 10.8% |
| Widowed | 6.7% | 7.1% | 5.6% |
| space5 | | | |
| Household Size | 2.29 | 2.11 | 2.60 |
| Households | 12,313 | 5,948 | 124,010,992 |
| Family Households | 6,374 | 3,256 | 80,755,759 |
| Married couple, w/children | 22.1% | 16.3% | 30.5% |
| Married couple, no children | 32.0% | 40.0% | 42.9% |
| Non Family Households | 5,939 | 2,692 | 43,255,233 |
| Single householder, w/children | 31.1% | 27.2% | 15.8% |
| Single householder, no children | 14.8% | 16.4% | 10.8% |