| | Carnegie, PA | New Orleans, LA | United States |
| Population | 8,100 | 383,974 | 329,725,481 |
| Female Population | 50.7% | 52.5% | 50.5% |
| Male Population | 49.3% | 47.5% | 49.5% |
| Median Age | 41.3 | 37.7 | 38.4 |
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| Population - 2010 | 7,983 | 347,789 | 309,327,143 |
| Population - 2000 | 8,389 | 484,674 | 285,036,114 |
| Population - 1990 | 9,278 | 496,938 | 251,960,433 |
| Pop. 2000 to Now | -7.6% | -19.6% | 15.6% |
| Pop. 1990 to Now | -16.5% | -21.6% | 30.8% |
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| Population Density | 5,006.2 | 2,266.3 | 93.4 |
| Land Area | 1.6 | 169.4 | 3,531,905.4 |
| Water Area | 0.0 | 180.4 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Carnegie, PA | New Orleans, LA | United States |
| Age 0 to 4 | 8.2% | 5.7% | 5.9% |
| Age 5 to 9 | 3.4% | 5.4% | 6.1% |
| Age 10 to 14 | 2.8% | 5.7% | 6.6% |
| Age 15 to 17 | 1.5% | 3.2% | 3.9% |
| Age 18 to 20 | 1.8% | 4.0% | 4.0% |
| Age 21 to 24 | 4.4% | 4.4% | 5.2% |
| Age 25 to 34 | 18.8% | 17.1% | 13.8% |
| Age 35 to 44 | 11.8% | 14.2% | 12.9% |
| Age 45 to 54 | 10.7% | 11.9% | 12.6% |
| Age 55 to 59 | 6.8% | 6.6% | 6.7% |
| Age 60 to 64 | 10.2% | 6.6% | 6.3% |
| Age 65 to 74 | 12.3% | 9.7% | 9.6% |
| Age 75 to 84 | 4.4% | 3.8% | 4.5% |
| Age 85 and over | 3.0% | 1.7% | 1.9% |
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| Race | | | |
| | Carnegie, PA | New Orleans, LA | United States |
| White | 79.8% | 30.6% | 59.4% |
| Black | 12.4% | 57.6% | 12.2% |
| Asian | 2.1% | 2.7% | 5.6% |
| Native American | 0.3% | 0.1% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.1% | 0.8% | 0.4% |
| Two or More Races | 3.1% | 2.6% | 3.2% |
| Hispanic | 2.3% | 5.6% | 18.4% |
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| Marriage & Family | | | |
| | Carnegie, PA | New Orleans, LA | United States |
| Married Population | 39.7% | 32.0% | 49.8% |
| Currently Married | 37.7% | 29.4% | 48.0% |
| Married but Separated | 2.0% | 2.6% | 1.8% |
| Single Population | 60.3% | 68.0% | 50.2% |
| Never Married | 37.0% | 49.7% | 33.8% |
| Divorced | 13.6% | 12.8% | 10.8% |
| Widowed | 9.7% | 5.5% | 5.6% |
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| Household Size | 1.93 | 2.37 | 2.60 |
| Households | 4,190 | 156,586 | 124,010,992 |
| Family Households | 1,828 | 71,845 | 80,755,759 |
| Married couple, w/children | 17.0% | 19.8% | 30.5% |
| Married couple, no children | 49.6% | 37.4% | 42.9% |
| Non Family Households | 2,362 | 84,741 | 43,255,233 |
| Single householder, w/children | 19.9% | 26.1% | 15.8% |
| Single householder, no children | 13.6% | 16.8% | 10.8% |