| | Ross township (Allegheny County), PA | Plum, PA | United States |
| Population | 33,229 | 27,123 | 329,725,481 |
| Female Population | 53.8% | 50.8% | 50.5% |
| Male Population | 46.2% | 49.2% | 49.5% |
| Median Age | 42.2 | 44.1 | 38.4 |
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| Population - 2010 | 31,105 | 27,137 | 309,327,143 |
| Population - 2000 | 32,551 | 26,940 | 285,036,114 |
| Population - 1990 | 33,482 | 25,609 | 251,960,433 |
| Pop. 2000 to Now | -6.7% | 0.2% | 15.6% |
| Pop. 1990 to Now | -9.3% | 5.4% | 30.8% |
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| Population Density | 2,295.6 | 948.9 | 93.4 |
| Land Area | 14.5 | 28.6 | 3,531,905.4 |
| Water Area | 0.0 | 0.4 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Ross township (Allegheny County), PA | Plum, PA | United States |
| Age 0 to 4 | 6.7% | 4.7% | 5.9% |
| Age 5 to 9 | 4.7% | 6.8% | 6.1% |
| Age 10 to 14 | 5.3% | 5.4% | 6.6% |
| Age 15 to 17 | 2.4% | 4.5% | 3.9% |
| Age 18 to 20 | 1.6% | 2.8% | 4.0% |
| Age 21 to 24 | 3.6% | 3.5% | 5.2% |
| Age 25 to 34 | 15.3% | 10.7% | 13.8% |
| Age 35 to 44 | 13.7% | 12.6% | 12.9% |
| Age 45 to 54 | 10.3% | 13.0% | 12.6% |
| Age 55 to 59 | 6.1% | 8.0% | 6.7% |
| Age 60 to 64 | 7.7% | 8.1% | 6.3% |
| Age 65 to 74 | 13.6% | 10.8% | 9.6% |
| Age 75 to 84 | 5.8% | 5.2% | 4.5% |
| Age 85 and over | 3.3% | 3.9% | 1.9% |
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| Race | | | |
| | Ross township (Allegheny County), PA | Plum, PA | United States |
| White | 91.1% | 91.2% | 59.4% |
| Black | 2.8% | 4.5% | 12.2% |
| Asian | 3.2% | 0.7% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.1% | 0.6% | 0.4% |
| Two or More Races | 1.5% | 2.2% | 3.2% |
| Hispanic | 1.4% | 0.8% | 18.4% |
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| Marriage & Family | | | |
| | Ross township (Allegheny County), PA | Plum, PA | United States |
| Married Population | 56.8% | 59.7% | 49.8% |
| Currently Married | 55.6% | 58.6% | 48.0% |
| Married but Separated | 1.1% | 1.1% | 1.8% |
| Single Population | 43.2% | 40.3% | 50.2% |
| Never Married | 25.6% | 26.4% | 33.8% |
| Divorced | 9.8% | 6.3% | 10.8% |
| Widowed | 7.8% | 7.6% | 5.6% |
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| Household Size | 2.24 | 2.50 | 2.60 |
| Households | 14,585 | 10,834 | 124,010,992 |
| Family Households | 8,804 | 7,776 | 80,755,759 |
| Married couple, w/children | 30.9% | 31.0% | 30.5% |
| Married couple, no children | 53.0% | 52.0% | 42.9% |
| Non Family Households | 5,781 | 3,058 | 43,255,233 |
| Single householder, w/children | 6.8% | 9.4% | 15.8% |
| Single householder, no children | 9.3% | 7.6% | 10.8% |