| | Niles, OH | Dover, OH | United States |
| Population | 18,319 | 13,083 | 329,725,481 |
| Female Population | 53.1% | 53.3% | 50.5% |
| Male Population | 46.9% | 46.7% | 49.5% |
| Median Age | 45.4 | 38.8 | 38.4 |
| space3 | | | |
| Population - 2010 | 19,153 | 12,866 | 309,327,143 |
| Population - 2000 | 20,932 | 12,210 | 285,036,114 |
| Population - 1990 | 21,128 | 11,329 | 251,960,433 |
| Pop. 2000 to Now | -13.8% | 4.0% | 15.6% |
| Pop. 1990 to Now | -14.6% | 12.0% | 30.8% |
| space4 | | | |
| Population Density | 2,127.9 | 2,298.9 | 93.4 |
| Land Area | 8.6 | 5.7 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Niles, OH | Dover, OH | United States |
| Age 0 to 4 | 3.5% | 4.4% | 5.9% |
| Age 5 to 9 | 4.0% | 5.8% | 6.1% |
| Age 10 to 14 | 5.0% | 9.6% | 6.6% |
| Age 15 to 17 | 3.7% | 6.2% | 3.9% |
| Age 18 to 20 | 3.4% | 3.1% | 4.0% |
| Age 21 to 24 | 5.1% | 5.3% | 5.2% |
| Age 25 to 34 | 11.8% | 7.9% | 13.8% |
| Age 35 to 44 | 12.9% | 15.5% | 12.9% |
| Age 45 to 54 | 11.7% | 9.7% | 12.6% |
| Age 55 to 59 | 7.2% | 5.6% | 6.7% |
| Age 60 to 64 | 7.4% | 5.6% | 6.3% |
| Age 65 to 74 | 14.1% | 10.1% | 9.6% |
| Age 75 to 84 | 7.4% | 7.1% | 4.5% |
| Age 85 and over | 2.6% | 3.9% | 1.9% |
| space1 | | | |
| Race | | | |
| | Niles, OH | Dover, OH | United States |
| White | 90.0% | 93.0% | 59.4% |
| Black | 4.8% | 0.4% | 12.2% |
| Asian | 1.2% | 0.1% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 2.5% | 2.1% | 3.2% |
| Hispanic | 1.5% | 4.3% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Niles, OH | Dover, OH | United States |
| Married Population | 41.9% | 48.4% | 49.8% |
| Currently Married | 40.4% | 47.0% | 48.0% |
| Married but Separated | 1.5% | 1.4% | 1.8% |
| Single Population | 58.1% | 51.6% | 50.2% |
| Never Married | 34.4% | 31.5% | 33.8% |
| Divorced | 15.0% | 11.2% | 10.8% |
| Widowed | 8.7% | 8.9% | 5.6% |
| space5 | | | |
| Household Size | 2.16 | 2.51 | 2.60 |
| Households | 8,367 | 5,080 | 124,010,992 |
| Family Households | 4,429 | 3,002 | 80,755,759 |
| Married couple, w/children | 21.0% | 34.4% | 30.5% |
| Married couple, no children | 47.3% | 42.2% | 42.9% |
| Non Family Households | 3,938 | 2,078 | 43,255,233 |
| Single householder, w/children | 19.1% | 14.7% | 15.8% |
| Single householder, no children | 12.6% | 8.7% | 10.8% |