| | Mason, OH | Maineville, OH | United States |
| Population | 34,337 | 1,990 | 329,725,481 |
| Female Population | 49.5% | 47.8% | 50.5% |
| Male Population | 50.5% | 52.2% | 49.5% |
| Median Age | 42.1 | 31.6 | 38.4 |
| space3 | | | |
| Population - 2010 | 30,912 | 974 | 309,327,143 |
| Population - 2000 | 22,016 | 885 | 285,036,114 |
| Population - 1990 | 11,452 | 359 | 251,960,433 |
| Pop. 2000 to Now | 55.8% | 27.9% | 15.6% |
| Pop. 1990 to Now | 199.5% | 215.3% | 30.8% |
| space4 | | | |
| Population Density | 1,783.9 | 1,252.4 | 93.4 |
| Land Area | 19.2 | 1.6 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Mason, OH | Maineville, OH | United States |
| Age 0 to 4 | 4.6% | 13.6% | 5.9% |
| Age 5 to 9 | 5.4% | 6.2% | 6.1% |
| Age 10 to 14 | 9.7% | 12.4% | 6.6% |
| Age 15 to 17 | 6.6% | 2.2% | 3.9% |
| Age 18 to 20 | 3.2% | 1.6% | 4.0% |
| Age 21 to 24 | 3.3% | 3.1% | 5.2% |
| Age 25 to 34 | 8.2% | 16.4% | 13.8% |
| Age 35 to 44 | 14.8% | 17.4% | 12.9% |
| Age 45 to 54 | 16.0% | 6.2% | 12.6% |
| Age 55 to 59 | 7.6% | 6.4% | 6.7% |
| Age 60 to 64 | 7.9% | 4.8% | 6.3% |
| Age 65 to 74 | 5.8% | 6.6% | 9.6% |
| Age 75 to 84 | 5.0% | 3.0% | 4.5% |
| Age 85 and over | 2.0% | 0.2% | 1.9% |
| space1 | | | |
| Race | | | |
| | Mason, OH | Maineville, OH | United States |
| White | 75.7% | 93.9% | 59.4% |
| Black | 4.7% | 0.2% | 12.2% |
| Asian | 14.1% | 0.3% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.2% | 0.9% | 0.4% |
| Two or More Races | 1.7% | 0.7% | 3.2% |
| Hispanic | 3.6% | 4.1% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Mason, OH | Maineville, OH | United States |
| Married Population | 60.6% | 57.0% | 49.8% |
| Currently Married | 60.1% | 55.3% | 48.0% |
| Married but Separated | 0.6% | 1.7% | 1.8% |
| Single Population | 39.4% | 43.0% | 50.2% |
| Never Married | 24.5% | 20.6% | 33.8% |
| Divorced | 9.6% | 17.9% | 10.8% |
| Widowed | 5.3% | 4.5% | 5.6% |
| space5 | | | |
| Household Size | 2.69 | 3.00 | 2.60 |
| Households | 12,648 | 661 | 124,010,992 |
| Family Households | 9,695 | 427 | 80,755,759 |
| Married couple, w/children | 40.5% | 45.9% | 30.5% |
| Married couple, no children | 42.2% | 30.9% | 42.9% |
| Non Family Households | 2,953 | 234 | 43,255,233 |
| Single householder, w/children | 10.8% | 18.5% | 15.8% |
| Single householder, no children | 6.5% | 4.7% | 10.8% |