| | Plain City, OH | Gahanna, OH | United States |
| Population | 3,882 | 35,626 | 329,725,481 |
| Female Population | 48.4% | 52.0% | 50.5% |
| Male Population | 51.6% | 48.0% | 49.5% |
| Median Age | 39 | 39.1 | 38.4 |
| space3 | | | |
| Population - 2010 | 4,213 | 33,274 | 309,327,143 |
| Population - 2000 | 2,832 | 32,636 | 285,036,114 |
| Population - 1990 | 2,278 | 27,791 | 251,960,433 |
| Pop. 2000 to Now | 68.1% | 8.9% | 15.6% |
| Pop. 1990 to Now | 109.0% | 27.9% | 30.8% |
| space4 | | | |
| Population Density | 1,605.5 | 2,866.6 | 93.4 |
| Land Area | 2.4 | 12.4 | 3,531,905.4 |
| Water Area | 0.0 | 0.2 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Plain City, OH | Gahanna, OH | United States |
| Age 0 to 4 | 8.4% | 5.3% | 5.9% |
| Age 5 to 9 | 7.6% | 5.9% | 6.1% |
| Age 10 to 14 | 6.9% | 7.3% | 6.6% |
| Age 15 to 17 | 3.3% | 5.5% | 3.9% |
| Age 18 to 20 | 2.6% | 2.8% | 4.0% |
| Age 21 to 24 | 3.9% | 3.2% | 5.2% |
| Age 25 to 34 | 13.8% | 13.4% | 13.8% |
| Age 35 to 44 | 11.7% | 14.0% | 12.9% |
| Age 45 to 54 | 10.0% | 12.9% | 12.6% |
| Age 55 to 59 | 6.3% | 6.6% | 6.7% |
| Age 60 to 64 | 7.8% | 6.8% | 6.3% |
| Age 65 to 74 | 7.3% | 10.8% | 9.6% |
| Age 75 to 84 | 9.0% | 3.7% | 4.5% |
| Age 85 and over | 1.4% | 1.9% | 1.9% |
| space1 | | | |
| Race | | | |
| | Plain City, OH | Gahanna, OH | United States |
| White | 93.5% | 75.3% | 59.4% |
| Black | 0.0% | 12.7% | 12.2% |
| Asian | 1.7% | 3.6% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 1.0% | 0.4% |
| Two or More Races | 3.6% | 4.5% | 3.2% |
| Hispanic | 1.2% | 2.9% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Plain City, OH | Gahanna, OH | United States |
| Married Population | 63.3% | 57.1% | 49.8% |
| Currently Married | 61.6% | 55.1% | 48.0% |
| Married but Separated | 1.7% | 1.9% | 1.8% |
| Single Population | 36.7% | 42.9% | 50.2% |
| Never Married | 24.3% | 27.7% | 33.8% |
| Divorced | 7.3% | 9.6% | 10.8% |
| Widowed | 5.1% | 5.6% | 5.6% |
| space5 | | | |
| Household Size | 2.55 | 2.48 | 2.60 |
| Households | 1,520 | 14,304 | 124,010,992 |
| Family Households | 1,118 | 9,970 | 80,755,759 |
| Married couple, w/children | 35.0% | 32.7% | 30.5% |
| Married couple, no children | 42.3% | 45.7% | 42.9% |
| Non Family Households | 402 | 4,334 | 43,255,233 |
| Single householder, w/children | 15.3% | 14.0% | 15.8% |
| Single householder, no children | 7.4% | 7.6% | 10.8% |