| | Eaton Rapids, MI | Big Rapids, MI | United States |
| Population | 5,211 | 9,105 | 329,725,481 |
| Female Population | 50.4% | 46.3% | 50.5% |
| Male Population | 49.6% | 53.7% | 49.5% |
| Median Age | 38.2 | 22 | 38.4 |
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| Population - 2010 | 5,216 | 10,434 | 309,327,143 |
| Population - 2000 | 5,330 | 10,849 | 285,036,114 |
| Population - 1990 | 4,695 | 12,603 | 251,960,433 |
| Pop. 2000 to Now | -2.0% | -4.1% | 15.6% |
| Pop. 1990 to Now | 11.2% | -17.4% | 30.8% |
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| Population Density | 1,477.9 | 2,048.4 | 93.4 |
| Land Area | 3.5 | 4.4 | 3,531,905.4 |
| Water Area | 0.1 | 0.1 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Eaton Rapids, MI | Big Rapids, MI | United States |
| Age 0 to 4 | 5.3% | 3.8% | 5.9% |
| Age 5 to 9 | 7.3% | 3.4% | 6.1% |
| Age 10 to 14 | 7.8% | 3.4% | 6.6% |
| Age 15 to 17 | 4.9% | 2.2% | 3.9% |
| Age 18 to 20 | 4.2% | 29.3% | 4.0% |
| Age 21 to 24 | 7.0% | 21.9% | 5.2% |
| Age 25 to 34 | 8.8% | 9.0% | 13.8% |
| Age 35 to 44 | 15.2% | 8.5% | 12.9% |
| Age 45 to 54 | 13.2% | 5.2% | 12.6% |
| Age 55 to 59 | 5.2% | 2.3% | 6.7% |
| Age 60 to 64 | 5.5% | 3.2% | 6.3% |
| Age 65 to 74 | 9.3% | 4.7% | 9.6% |
| Age 75 to 84 | 4.7% | 2.0% | 4.5% |
| Age 85 and over | 1.6% | 1.0% | 1.9% |
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| Race | | | |
| | Eaton Rapids, MI | Big Rapids, MI | United States |
| White | 91.7% | 82.2% | 59.4% |
| Black | 0.4% | 8.3% | 12.2% |
| Asian | 0.0% | 1.8% | 5.6% |
| Native American | 0.1% | 1.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 0.7% | 1.4% | 3.2% |
| Hispanic | 7.0% | 5.1% | 18.4% |
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| Marriage & Family | | | |
| | Eaton Rapids, MI | Big Rapids, MI | United States |
| Married Population | 47.8% | 17.3% | 49.8% |
| Currently Married | 47.2% | 16.7% | 48.0% |
| Married but Separated | 0.6% | 0.6% | 1.8% |
| Single Population | 52.2% | 82.7% | 50.2% |
| Never Married | 30.4% | 70.6% | 33.8% |
| Divorced | 15.5% | 8.7% | 10.8% |
| Widowed | 6.3% | 3.4% | 5.6% |
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| Household Size | 2.63 | 2.09 | 2.60 |
| Households | 1,983 | 3,085 | 124,010,992 |
| Family Households | 1,308 | 1,044 | 80,755,759 |
| Married couple, w/children | 33.7% | 34.5% | 30.5% |
| Married couple, no children | 35.6% | 29.0% | 42.9% |
| Non Family Households | 675 | 2,041 | 43,255,233 |
| Single householder, w/children | 18.4% | 31.5% | 15.8% |
| Single householder, no children | 12.3% | 5.0% | 10.8% |