| | Harrison, MI | Port Huron, MI | United States |
| Population | 2,173 | 29,009 | 329,725,481 |
| Female Population | 46.9% | 50.1% | 50.5% |
| Male Population | 53.1% | 49.9% | 49.5% |
| Median Age | 49.8 | 39 | 38.4 |
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| Population - 2010 | 2,106 | 30,110 | 309,327,143 |
| Population - 2000 | 2,108 | 32,338 | 285,036,114 |
| Population - 1990 | 1,835 | 33,694 | 251,960,433 |
| Pop. 2000 to Now | -2.2% | -11.5% | 15.6% |
| Pop. 1990 to Now | 12.4% | -15.0% | 30.8% |
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| Population Density | 584.9 | 3,580.5 | 93.4 |
| Land Area | 3.7 | 8.1 | 3,531,905.4 |
| Water Area | 0.3 | 4.2 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Harrison, MI | Port Huron, MI | United States |
| Age 0 to 4 | 4.1% | 5.8% | 5.9% |
| Age 5 to 9 | 3.2% | 6.1% | 6.1% |
| Age 10 to 14 | 6.7% | 6.4% | 6.6% |
| Age 15 to 17 | 3.3% | 4.0% | 3.9% |
| Age 18 to 20 | 0.9% | 3.8% | 4.0% |
| Age 21 to 24 | 3.1% | 5.5% | 5.2% |
| Age 25 to 34 | 12.8% | 14.3% | 13.8% |
| Age 35 to 44 | 10.5% | 12.0% | 12.9% |
| Age 45 to 54 | 13.1% | 12.2% | 12.6% |
| Age 55 to 59 | 6.7% | 6.9% | 6.7% |
| Age 60 to 64 | 8.9% | 6.5% | 6.3% |
| Age 65 to 74 | 14.8% | 10.0% | 9.6% |
| Age 75 to 84 | 6.1% | 3.3% | 4.5% |
| Age 85 and over | 5.8% | 3.3% | 1.9% |
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| Race | | | |
| | Harrison, MI | Port Huron, MI | United States |
| White | 94.5% | 77.2% | 59.4% |
| Black | 3.2% | 7.5% | 12.2% |
| Asian | 0.0% | 0.6% | 5.6% |
| Native American | 0.3% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.1% | 0.2% |
| Other | 0.0% | 0.2% | 0.4% |
| Two or More Races | 1.2% | 6.2% | 3.2% |
| Hispanic | 0.8% | 8.1% | 18.4% |
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| Marriage & Family | | | |
| | Harrison, MI | Port Huron, MI | United States |
| Married Population | 43.6% | 40.7% | 49.8% |
| Currently Married | 42.5% | 38.8% | 48.0% |
| Married but Separated | 1.1% | 2.0% | 1.8% |
| Single Population | 56.4% | 59.3% | 50.2% |
| Never Married | 27.1% | 37.1% | 33.8% |
| Divorced | 18.8% | 16.5% | 10.8% |
| Widowed | 10.5% | 5.7% | 5.6% |
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| Household Size | 2.28 | 2.35 | 2.60 |
| Households | 883 | 12,179 | 124,010,992 |
| Family Households | 462 | 7,301 | 80,755,759 |
| Married couple, w/children | 16.7% | 18.7% | 30.5% |
| Married couple, no children | 54.3% | 39.4% | 42.9% |
| Non Family Households | 421 | 4,878 | 43,255,233 |
| Single householder, w/children | 21.0% | 27.4% | 15.8% |
| Single householder, no children | 8.0% | 14.5% | 10.8% |