| | Allendale, MI | Alma, MI | United States |
| Population | 23,999 | 9,426 | 329,725,481 |
| Female Population | 55.2% | 52.4% | 50.5% |
| Male Population | 44.8% | 47.6% | 49.5% |
| Median Age | 21.4 | 32.4 | 38.4 |
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| Population - 2010 | 16,652 | 9,357 | 309,327,143 |
| Population - 2000 | 11,555 | 9,275 | 285,036,114 |
| Population - 1990 | 6,950 | 9,034 | 251,960,433 |
| Pop. 2000 to Now | 82.3% | -5.1% | 15.6% |
| Pop. 1990 to Now | 203.0% | -2.5% | 30.8% |
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| Population Density | 1,056.0 | 1,599.8 | 93.4 |
| Land Area | 22.7 | 5.9 | 3,531,905.4 |
| Water Area | 0.9 | 0.2 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Allendale, MI | Alma, MI | United States |
| Age 0 to 4 | 4.4% | 5.2% | 5.9% |
| Age 5 to 9 | 3.2% | 6.7% | 6.1% |
| Age 10 to 14 | 4.1% | 3.7% | 6.6% |
| Age 15 to 17 | 3.4% | 3.1% | 3.9% |
| Age 18 to 20 | 30.9% | 13.1% | 4.0% |
| Age 21 to 24 | 20.4% | 6.7% | 5.2% |
| Age 25 to 34 | 9.2% | 13.9% | 13.8% |
| Age 35 to 44 | 6.5% | 9.9% | 12.9% |
| Age 45 to 54 | 5.6% | 8.8% | 12.6% |
| Age 55 to 59 | 2.9% | 4.4% | 6.7% |
| Age 60 to 64 | 4.4% | 7.8% | 6.3% |
| Age 65 to 74 | 3.3% | 9.0% | 9.6% |
| Age 75 to 84 | 1.1% | 4.1% | 4.5% |
| Age 85 and over | 0.5% | 3.6% | 1.9% |
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| Race | | | |
| | Allendale, MI | Alma, MI | United States |
| White | 89.2% | 85.0% | 59.4% |
| Black | 2.1% | 2.7% | 12.2% |
| Asian | 1.8% | 1.7% | 5.6% |
| Native American | 0.1% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.4% | 0.0% | 0.4% |
| Two or More Races | 2.3% | 1.2% | 3.2% |
| Hispanic | 4.1% | 9.3% | 18.4% |
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| Marriage & Family | | | |
| | Allendale, MI | Alma, MI | United States |
| Married Population | 26.2% | 42.5% | 49.8% |
| Currently Married | 26.0% | 40.7% | 48.0% |
| Married but Separated | 0.2% | 1.8% | 1.8% |
| Single Population | 73.8% | 57.5% | 50.2% |
| Never Married | 66.6% | 40.5% | 33.8% |
| Divorced | 5.9% | 11.8% | 10.8% |
| Widowed | 1.3% | 5.3% | 5.6% |
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| Household Size | 2.78 | 2.18 | 2.60 |
| Households | 7,070 | 3,581 | 124,010,992 |
| Family Households | 3,556 | 2,071 | 80,755,759 |
| Married couple, w/children | 36.2% | 21.2% | 30.5% |
| Married couple, no children | 37.3% | 51.2% | 42.9% |
| Non Family Households | 3,514 | 1,510 | 43,255,233 |
| Single householder, w/children | 12.3% | 19.0% | 15.8% |
| Single householder, no children | 14.2% | 8.5% | 10.8% |