| | Plymouth, MA | Melbourne, FL | United States |
| Population | 60,987 | 83,500 | 329,725,481 |
| Female Population | 50.8% | 51.8% | 50.5% |
| Male Population | 49.2% | 48.2% | 49.5% |
| Median Age | 47.9 | 42.4 | 38.4 |
| space3 | | | |
| Population - 2010 | 56,654 | 76,371 | 309,327,143 |
| Population - 2000 | 51,701 | 71,382 | 285,036,114 |
| Population - 1990 | 45,608 | 59,646 | 251,960,433 |
| Pop. 2000 to Now | 21.2% | 16.8% | 15.6% |
| Pop. 1990 to Now | 37.4% | 39.8% | 30.8% |
| space4 | | | |
| Population Density | 632.3 | 1,896.0 | 93.4 |
| Land Area | 96.4 | 44.0 | 3,531,905.4 |
| Water Area | 37.5 | 5.8 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Plymouth, MA | Melbourne, FL | United States |
| Age 0 to 4 | 4.2% | 4.7% | 5.9% |
| Age 5 to 9 | 5.0% | 4.6% | 6.1% |
| Age 10 to 14 | 4.7% | 5.6% | 6.6% |
| Age 15 to 17 | 3.1% | 3.2% | 3.9% |
| Age 18 to 20 | 2.3% | 4.0% | 4.0% |
| Age 21 to 24 | 3.8% | 5.2% | 5.2% |
| Age 25 to 34 | 12.3% | 14.7% | 13.8% |
| Age 35 to 44 | 11.0% | 10.4% | 12.9% |
| Age 45 to 54 | 13.2% | 11.8% | 12.6% |
| Age 55 to 59 | 8.6% | 7.4% | 6.7% |
| Age 60 to 64 | 8.7% | 6.9% | 6.3% |
| Age 65 to 74 | 14.6% | 11.9% | 9.6% |
| Age 75 to 84 | 6.2% | 5.8% | 4.5% |
| Age 85 and over | 2.3% | 3.9% | 1.9% |
| space1 | | | |
| Race | | | |
| | Plymouth, MA | Melbourne, FL | United States |
| White | 91.2% | 69.2% | 59.4% |
| Black | 1.3% | 9.6% | 12.2% |
| Asian | 0.9% | 4.0% | 5.6% |
| Native American | 0.0% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.2% | 0.2% |
| Other | 0.8% | 0.5% | 0.4% |
| Two or More Races | 3.0% | 4.1% | 3.2% |
| Hispanic | 2.7% | 12.4% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Plymouth, MA | Melbourne, FL | United States |
| Married Population | 57.5% | 43.7% | 49.8% |
| Currently Married | 56.2% | 41.9% | 48.0% |
| Married but Separated | 1.3% | 1.7% | 1.8% |
| Single Population | 42.5% | 56.3% | 50.2% |
| Never Married | 27.1% | 33.3% | 33.8% |
| Divorced | 9.4% | 15.0% | 10.8% |
| Widowed | 6.0% | 8.0% | 5.6% |
| space5 | | | |
| Household Size | 2.37 | 2.35 | 2.60 |
| Households | 24,985 | 34,473 | 124,010,992 |
| Family Households | 17,004 | 18,851 | 80,755,759 |
| Married couple, w/children | 25.8% | 24.4% | 30.5% |
| Married couple, no children | 56.0% | 46.0% | 42.9% |
| Non Family Households | 7,981 | 15,622 | 43,255,233 |
| Single householder, w/children | 9.7% | 16.5% | 15.8% |
| Single householder, no children | 8.4% | 13.1% | 10.8% |