| | Marathon, WI | Wausau, WI | United States |
| Population | 1,113 | 39,745 | 329,725,481 |
| Female Population | 50.1% | 51.6% | 50.5% |
| Male Population | 50.0% | 48.4% | 49.5% |
| Median Age | 52.1 | 38.6 | 38.4 |
| space3 | | | |
| Population - 2010 | 1,046 | 39,284 | 309,327,143 |
| Population - 2000 | 1,085 | 38,426 | 285,036,114 |
| Population - 1990 | 978 | 37,060 | 251,960,433 |
| Pop. 2000 to Now | 1.7% | 0.2% | 15.6% |
| Pop. 1990 to Now | 12.8% | 3.9% | 30.8% |
| space4 | | | |
| Population Density | 33.8 | 2,058.8 | 93.4 |
| Land Area | 32.9 | 19.3 | 3,531,905.4 |
| Water Area | 0.0 | 1.3 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Marathon, WI | Wausau, WI | United States |
| Age 0 to 4 | 3.4% | 6.3% | 5.9% |
| Age 5 to 9 | 5.8% | 6.3% | 6.1% |
| Age 10 to 14 | 8.4% | 5.9% | 6.6% |
| Age 15 to 17 | 3.9% | 3.9% | 3.9% |
| Age 18 to 20 | 1.1% | 3.1% | 4.0% |
| Age 21 to 24 | 3.1% | 5.1% | 5.2% |
| Age 25 to 34 | 7.2% | 14.9% | 13.8% |
| Age 35 to 44 | 12.1% | 12.6% | 12.9% |
| Age 45 to 54 | 12.0% | 11.2% | 12.6% |
| Age 55 to 59 | 12.8% | 6.0% | 6.7% |
| Age 60 to 64 | 9.8% | 7.4% | 6.3% |
| Age 65 to 74 | 12.4% | 9.9% | 9.6% |
| Age 75 to 84 | 3.5% | 4.5% | 4.5% |
| Age 85 and over | 4.7% | 3.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Marathon, WI | Wausau, WI | United States |
| White | 99.5% | 78.9% | 59.4% |
| Black | 0.0% | 0.7% | 12.2% |
| Asian | 0.2% | 11.6% | 5.6% |
| Native American | 0.0% | 0.3% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 0.4% | 3.9% | 3.2% |
| Hispanic | 0.0% | 4.6% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Marathon, WI | Wausau, WI | United States |
| Married Population | 70.7% | 46.5% | 49.8% |
| Currently Married | 70.3% | 45.3% | 48.0% |
| Married but Separated | 0.3% | 1.1% | 1.8% |
| Single Population | 29.3% | 53.5% | 50.2% |
| Never Married | 17.6% | 34.1% | 33.8% |
| Divorced | 5.9% | 12.8% | 10.8% |
| Widowed | 5.9% | 6.6% | 5.6% |
| space5 | | | |
| Household Size | 2.62 | 2.23 | 2.60 |
| Households | 425 | 17,370 | 124,010,992 |
| Family Households | 343 | 9,625 | 80,755,759 |
| Married couple, w/children | 26.2% | 27.5% | 30.5% |
| Married couple, no children | 67.9% | 44.5% | 42.9% |
| Non Family Households | 82 | 7,745 | 43,255,233 |
| Single householder, w/children | 1.5% | 20.6% | 15.8% |
| Single householder, no children | 4.4% | 7.5% | 10.8% |