| | Middletown, OH | Fortuna, CA | United States |
| Population | 50,114 | 12,480 | 329,725,481 |
| Female Population | 52.5% | 52.4% | 50.5% |
| Male Population | 47.5% | 47.6% | 49.5% |
| Median Age | 38.7 | 40.2 | 38.4 |
| space3 | | | |
| Population - 2010 | 48,739 | 12,030 | 309,327,143 |
| Population - 2000 | 51,605 | 10,497 | 285,036,114 |
| Population - 1990 | 46,022 | 8,788 | 251,960,433 |
| Pop. 2000 to Now | -5.2% | 15.3% | 15.6% |
| Pop. 1990 to Now | 6.3% | 37.8% | 30.8% |
| space4 | | | |
| Population Density | 1,917.0 | 2,444.7 | 93.4 |
| Land Area | 26.1 | 5.1 | 3,531,905.4 |
| Water Area | 0.3 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Middletown, OH | Fortuna, CA | United States |
| Age 0 to 4 | 5.4% | 5.6% | 5.9% |
| Age 5 to 9 | 6.3% | 7.3% | 6.1% |
| Age 10 to 14 | 6.9% | 4.8% | 6.6% |
| Age 15 to 17 | 3.2% | 5.1% | 3.9% |
| Age 18 to 20 | 3.3% | 4.7% | 4.0% |
| Age 21 to 24 | 7.8% | 4.8% | 5.2% |
| Age 25 to 34 | 12.8% | 12.6% | 13.8% |
| Age 35 to 44 | 10.9% | 11.0% | 12.9% |
| Age 45 to 54 | 12.2% | 12.6% | 12.6% |
| Age 55 to 59 | 6.9% | 8.7% | 6.7% |
| Age 60 to 64 | 7.4% | 7.0% | 6.3% |
| Age 65 to 74 | 10.7% | 8.0% | 9.6% |
| Age 75 to 84 | 4.0% | 4.3% | 4.5% |
| Age 85 and over | 2.2% | 3.6% | 1.9% |
| space1 | | | |
| Race | | | |
| | Middletown, OH | Fortuna, CA | United States |
| White | 77.9% | 68.4% | 59.4% |
| Black | 11.3% | 0.7% | 12.2% |
| Asian | 0.6% | 1.5% | 5.6% |
| Native American | 0.0% | 1.5% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.3% | 0.2% |
| Other | 0.2% | 0.2% | 0.4% |
| Two or More Races | 5.3% | 4.2% | 3.2% |
| Hispanic | 4.6% | 23.3% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Middletown, OH | Fortuna, CA | United States |
| Married Population | 40.5% | 45.9% | 49.8% |
| Currently Married | 36.9% | 44.0% | 48.0% |
| Married but Separated | 3.6% | 1.9% | 1.8% |
| Single Population | 59.5% | 54.1% | 50.2% |
| Never Married | 36.9% | 32.2% | 33.8% |
| Divorced | 14.3% | 14.2% | 10.8% |
| Widowed | 8.3% | 7.7% | 5.6% |
| space5 | | | |
| Household Size | 2.42 | 2.52 | 2.60 |
| Households | 20,441 | 4,901 | 124,010,992 |
| Family Households | 11,805 | 3,136 | 80,755,759 |
| Married couple, w/children | 19.6% | 26.6% | 30.5% |
| Married couple, no children | 39.8% | 40.6% | 42.9% |
| Non Family Households | 8,636 | 1,765 | 43,255,233 |
| Single householder, w/children | 27.1% | 22.5% | 15.8% |
| Single householder, no children | 13.4% | 10.3% | 10.8% |