| | Waltham, ME | Mariaville, ME | United States |
| Population | 290 | 542 | 329,725,481 |
| Female Population | 49.7% | 41.7% | 50.5% |
| Male Population | 50.4% | 58.3% | 49.5% |
| Median Age | 55 | 41.2 | 38.4 |
| space3 | | | |
| Population - 2010 | 352 | 514 | 309,327,143 |
| Population - 2000 | 306 | 414 | 285,036,114 |
| Population - 1990 | 276 | 270 | 251,960,433 |
| Pop. 2000 to Now | 11.1% | 30.4% | 15.6% |
| Pop. 1990 to Now | 23.2% | 100.0% | 30.8% |
| space4 | | | |
| Population Density | 9.8 | 14.0 | 93.4 |
| Land Area | 29.7 | 38.7 | 3,531,905.4 |
| Water Area | 3.2 | 8.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Waltham, ME | Mariaville, ME | United States |
| Age 0 to 4 | 5.9% | 4.4% | 5.9% |
| Age 5 to 9 | 6.9% | 3.7% | 6.1% |
| Age 10 to 14 | 0.0% | 3.5% | 6.6% |
| Age 15 to 17 | 3.1% | 4.2% | 3.9% |
| Age 18 to 20 | 0.3% | 3.5% | 4.0% |
| Age 21 to 24 | 3.1% | 9.8% | 5.2% |
| Age 25 to 34 | 11.0% | 14.9% | 13.8% |
| Age 35 to 44 | 11.4% | 10.7% | 12.9% |
| Age 45 to 54 | 8.3% | 9.6% | 12.6% |
| Age 55 to 59 | 7.9% | 7.2% | 6.7% |
| Age 60 to 64 | 7.2% | 14.4% | 6.3% |
| Age 65 to 74 | 23.8% | 11.6% | 9.6% |
| Age 75 to 84 | 8.6% | 2.4% | 4.5% |
| Age 85 and over | 2.4% | 0.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Waltham, ME | Mariaville, ME | United States |
| White | 97.6% | 87.1% | 59.4% |
| Black | 2.4% | 1.3% | 12.2% |
| Asian | 0.0% | 6.6% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 0.0% | 3.7% | 3.2% |
| Hispanic | 0.0% | 1.3% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Waltham, ME | Mariaville, ME | United States |
| Married Population | 57.3% | 53.0% | 49.8% |
| Currently Married | 56.9% | 51.4% | 48.0% |
| Married but Separated | 0.4% | 1.7% | 1.8% |
| Single Population | 42.7% | 47.0% | 50.2% |
| Never Married | 19.8% | 35.5% | 33.8% |
| Divorced | 17.8% | 10.4% | 10.8% |
| Widowed | 5.1% | 1.0% | 5.6% |
| space5 | | | |
| Household Size | 2.40 | 2.24 | 2.60 |
| Households | 121 | 242 | 124,010,992 |
| Family Households | 92 | 134 | 80,755,759 |
| Married couple, w/children | 19.6% | 25.4% | 30.5% |
| Married couple, no children | 60.9% | 64.9% | 42.9% |
| Non Family Households | 29 | 108 | 43,255,233 |
| Single householder, w/children | 14.1% | 9.7% | 15.8% |
| Single householder, no children | 5.4% | 0.0% | 10.8% |