| | Marysville, OH | Portsmouth, OH | United States |
| Population | 24,922 | 18,369 | 329,725,481 |
| Female Population | 55.5% | 53.3% | 50.5% |
| Male Population | 44.5% | 46.7% | 49.5% |
| Median Age | 37 | 36.5 | 38.4 |
| space3 | | | |
| Population - 2010 | 22,217 | 20,168 | 309,327,143 |
| Population - 2000 | 15,942 | 20,909 | 285,036,114 |
| Population - 1990 | 9,656 | 22,676 | 251,960,433 |
| Pop. 2000 to Now | 56.7% | -5.6% | 15.6% |
| Pop. 1990 to Now | 158.7% | -12.9% | 30.8% |
| space4 | | | |
| Population Density | 1,529.1 | 1,711.3 | 93.4 |
| Land Area | 16.3 | 10.7 | 3,531,905.4 |
| Water Area | 0.3 | 0.3 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Marysville, OH | Portsmouth, OH | United States |
| Age 0 to 4 | 5.3% | 5.8% | 5.9% |
| Age 5 to 9 | 6.3% | 6.6% | 6.1% |
| Age 10 to 14 | 5.1% | 6.0% | 6.6% |
| Age 15 to 17 | 3.9% | 3.9% | 3.9% |
| Age 18 to 20 | 2.9% | 5.0% | 4.0% |
| Age 21 to 24 | 5.7% | 6.8% | 5.2% |
| Age 25 to 34 | 17.1% | 14.0% | 13.8% |
| Age 35 to 44 | 17.8% | 11.6% | 12.9% |
| Age 45 to 54 | 13.0% | 9.5% | 12.6% |
| Age 55 to 59 | 6.7% | 6.7% | 6.7% |
| Age 60 to 64 | 5.3% | 6.1% | 6.3% |
| Age 65 to 74 | 6.9% | 10.2% | 9.6% |
| Age 75 to 84 | 2.2% | 6.0% | 4.5% |
| Age 85 and over | 1.6% | 1.7% | 1.9% |
| space1 | | | |
| Race | | | |
| | Marysville, OH | Portsmouth, OH | United States |
| White | 87.6% | 85.3% | 59.4% |
| Black | 3.9% | 6.4% | 12.2% |
| Asian | 2.1% | 1.2% | 5.6% |
| Native American | 0.1% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.1% | 0.0% | 0.4% |
| Two or More Races | 2.5% | 4.2% | 3.2% |
| Hispanic | 3.6% | 2.8% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Marysville, OH | Portsmouth, OH | United States |
| Married Population | 48.9% | 35.8% | 49.8% |
| Currently Married | 47.1% | 32.5% | 48.0% |
| Married but Separated | 1.8% | 3.4% | 1.8% |
| Single Population | 51.1% | 64.2% | 50.2% |
| Never Married | 33.5% | 41.0% | 33.8% |
| Divorced | 13.6% | 14.4% | 10.8% |
| Widowed | 4.1% | 8.8% | 5.6% |
| space5 | | | |
| Household Size | 2.48 | 2.35 | 2.60 |
| Households | 8,769 | 7,259 | 124,010,992 |
| Family Households | 5,779 | 3,950 | 80,755,759 |
| Married couple, w/children | 34.2% | 22.2% | 30.5% |
| Married couple, no children | 43.6% | 33.4% | 42.9% |
| Non Family Households | 2,990 | 3,309 | 43,255,233 |
| Single householder, w/children | 16.0% | 28.5% | 15.8% |
| Single householder, no children | 6.2% | 15.8% | 10.8% |