| | Avoca, WI | Mountain, WI | United States |
| Population | 555 | 972 | 329,725,481 |
| Female Population | 48.5% | 50.0% | 50.5% |
| Male Population | 51.5% | 50.0% | 49.5% |
| Median Age | 40.6 | 56.7 | 38.4 |
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| Population - 2010 | 637 | 823 | 309,327,143 |
| Population - 2000 | 608 | 860 | 285,036,114 |
| Population - 1990 | 474 | 637 | 251,960,433 |
| Pop. 2000 to Now | 2.0% | -1.1% | 15.6% |
| Pop. 1990 to Now | 30.8% | 33.6% | 30.8% |
| space4 | | | |
| Population Density | 246.6 | 13.6 | 93.4 |
| Land Area | 2.3 | 71.6 | 3,531,905.4 |
| Water Area | 0.2 | 1.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Avoca, WI | Mountain, WI | United States |
| Age 0 to 4 | 8.6% | 2.6% | 5.9% |
| Age 5 to 9 | 2.0% | 7.0% | 6.1% |
| Age 10 to 14 | 4.0% | 5.7% | 6.6% |
| Age 15 to 17 | 4.0% | 2.4% | 3.9% |
| Age 18 to 20 | 3.8% | 2.3% | 4.0% |
| Age 21 to 24 | 9.2% | 2.6% | 5.2% |
| Age 25 to 34 | 12.4% | 4.7% | 13.8% |
| Age 35 to 44 | 8.8% | 10.2% | 12.9% |
| Age 45 to 54 | 15.9% | 10.3% | 12.6% |
| Age 55 to 59 | 5.4% | 9.7% | 6.7% |
| Age 60 to 64 | 6.3% | 14.7% | 6.3% |
| Age 65 to 74 | 10.1% | 20.8% | 9.6% |
| Age 75 to 84 | 6.3% | 3.7% | 4.5% |
| Age 85 and over | 3.2% | 3.5% | 1.9% |
| space1 | | | |
| Race | | | |
| | Avoca, WI | Mountain, WI | United States |
| White | 94.2% | 97.8% | 59.4% |
| Black | 4.1% | 0.0% | 12.2% |
| Asian | 0.7% | 0.0% | 5.6% |
| Native American | 0.0% | 1.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 0.9% | 0.0% | 3.2% |
| Hispanic | 0.0% | 1.0% | 18.4% |
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| Marriage & Family | | | |
| | Avoca, WI | Mountain, WI | United States |
| Married Population | 46.2% | 51.9% | 49.8% |
| Currently Married | 44.9% | 50.2% | 48.0% |
| Married but Separated | 1.3% | 1.7% | 1.8% |
| Single Population | 53.8% | 48.1% | 50.2% |
| Never Married | 36.1% | 20.6% | 33.8% |
| Divorced | 10.1% | 14.2% | 10.8% |
| Widowed | 7.6% | 13.2% | 5.6% |
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| Household Size | 2.41 | 1.97 | 2.60 |
| Households | 229 | 493 | 124,010,992 |
| Family Households | 172 | 288 | 80,755,759 |
| Married couple, w/children | 9.3% | 11.8% | 30.5% |
| Married couple, no children | 54.1% | 66.0% | 42.9% |
| Non Family Households | 57 | 205 | 43,255,233 |
| Single householder, w/children | 25.6% | 13.9% | 15.8% |
| Single householder, no children | 11.0% | 8.3% | 10.8% |