| | Mount Pleasant, IA | Hannibal, MO | United States |
| Population | 8,996 | 17,165 | 329,725,481 |
| Female Population | 44.4% | 52.5% | 50.5% |
| Male Population | 55.6% | 47.5% | 49.5% |
| Median Age | 39 | 38 | 38.4 |
| space3 | | | |
| Population - 2010 | 8,653 | 17,771 | 309,327,143 |
| Population - 2000 | 8,751 | 17,757 | 285,036,114 |
| Population - 1990 | 8,027 | 18,004 | 251,960,433 |
| Pop. 2000 to Now | -2.8% | -2.9% | 15.6% |
| Pop. 1990 to Now | 6.0% | -4.2% | 30.8% |
| space4 | | | |
| Population Density | 1,046.7 | 1,090.9 | 93.4 |
| Land Area | 8.6 | 15.7 | 3,531,905.4 |
| Water Area | 0.0 | 0.5 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Mount Pleasant, IA | Hannibal, MO | United States |
| Age 0 to 4 | 4.1% | 6.3% | 5.9% |
| Age 5 to 9 | 3.8% | 6.1% | 6.1% |
| Age 10 to 14 | 5.4% | 7.8% | 6.6% |
| Age 15 to 17 | 3.2% | 3.5% | 3.9% |
| Age 18 to 20 | 6.0% | 5.1% | 4.0% |
| Age 21 to 24 | 8.4% | 5.9% | 5.2% |
| Age 25 to 34 | 13.8% | 11.8% | 13.8% |
| Age 35 to 44 | 12.3% | 10.3% | 12.9% |
| Age 45 to 54 | 10.5% | 10.7% | 12.6% |
| Age 55 to 59 | 8.0% | 5.6% | 6.7% |
| Age 60 to 64 | 6.7% | 8.2% | 6.3% |
| Age 65 to 74 | 10.0% | 10.7% | 9.6% |
| Age 75 to 84 | 4.7% | 4.7% | 4.5% |
| Age 85 and over | 3.0% | 3.1% | 1.9% |
| space1 | | | |
| Race | | | |
| | Mount Pleasant, IA | Hannibal, MO | United States |
| White | 77.9% | 87.1% | 59.4% |
| Black | 5.1% | 6.1% | 12.2% |
| Asian | 4.8% | 0.5% | 5.6% |
| Native American | 0.4% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.1% | 0.2% | 0.2% |
| Other | 0.8% | 0.3% | 0.4% |
| Two or More Races | 2.3% | 2.7% | 3.2% |
| Hispanic | 8.6% | 3.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Mount Pleasant, IA | Hannibal, MO | United States |
| Married Population | 45.6% | 45.5% | 49.8% |
| Currently Married | 45.0% | 44.2% | 48.0% |
| Married but Separated | 0.6% | 1.3% | 1.8% |
| Single Population | 54.4% | 54.5% | 50.2% |
| Never Married | 37.8% | 31.9% | 33.8% |
| Divorced | 10.2% | 15.2% | 10.8% |
| Widowed | 6.5% | 7.4% | 5.6% |
| space5 | | | |
| Household Size | 2.33 | 2.28 | 2.60 |
| Households | 3,266 | 6,988 | 124,010,992 |
| Family Households | 2,114 | 4,195 | 80,755,759 |
| Married couple, w/children | 31.1% | 26.5% | 30.5% |
| Married couple, no children | 46.9% | 42.2% | 42.9% |
| Non Family Households | 1,152 | 2,793 | 43,255,233 |
| Single householder, w/children | 12.7% | 24.6% | 15.8% |
| Single householder, no children | 9.3% | 6.7% | 10.8% |