| | Lyndhurst, NJ | Kearny, NJ | United States |
| Population | 22,315 | 41,790 | 329,725,481 |
| Female Population | 49.7% | 47.8% | 50.5% |
| Male Population | 50.3% | 52.2% | 49.5% |
| Median Age | 41.8 | 38.2 | 38.4 |
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| Population - 2010 | 20,570 | 40,714 | 309,327,143 |
| Population - 2000 | 19,383 | 40,513 | 285,036,114 |
| Population - 1990 | 18,262 | 34,874 | 251,960,433 |
| Pop. 2000 to Now | 17.5% | 0.0% | 15.6% |
| Pop. 1990 to Now | 24.8% | 16.2% | 30.8% |
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| Population Density | 4,902.2 | 4,725.2 | 93.4 |
| Land Area | 4.6 | 8.8 | 3,531,905.4 |
| Water Area | 0.3 | 1.4 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Lyndhurst, NJ | Kearny, NJ | United States |
| Age 0 to 4 | 4.2% | 7.3% | 5.9% |
| Age 5 to 9 | 4.4% | 5.6% | 6.1% |
| Age 10 to 14 | 5.9% | 5.0% | 6.6% |
| Age 15 to 17 | 3.0% | 3.3% | 3.9% |
| Age 18 to 20 | 1.8% | 2.5% | 4.0% |
| Age 21 to 24 | 7.3% | 4.9% | 5.2% |
| Age 25 to 34 | 12.4% | 16.5% | 13.8% |
| Age 35 to 44 | 14.7% | 15.1% | 12.9% |
| Age 45 to 54 | 13.7% | 14.0% | 12.6% |
| Age 55 to 59 | 7.5% | 7.0% | 6.7% |
| Age 60 to 64 | 8.7% | 5.7% | 6.3% |
| Age 65 to 74 | 9.1% | 8.4% | 9.6% |
| Age 75 to 84 | 5.3% | 3.4% | 4.5% |
| Age 85 and over | 2.1% | 1.3% | 1.9% |
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| Race | | | |
| | Lyndhurst, NJ | Kearny, NJ | United States |
| White | 64.9% | 32.5% | 59.4% |
| Black | 2.1% | 3.7% | 12.2% |
| Asian | 5.8% | 4.0% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.4% | 1.7% | 0.4% |
| Two or More Races | 0.8% | 2.8% | 3.2% |
| Hispanic | 25.9% | 55.3% | 18.4% |
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| Marriage & Family | | | |
| | Lyndhurst, NJ | Kearny, NJ | United States |
| Married Population | 48.2% | 51.3% | 49.8% |
| Currently Married | 47.2% | 49.0% | 48.0% |
| Married but Separated | 1.0% | 2.3% | 1.8% |
| Single Population | 51.8% | 48.7% | 50.2% |
| Never Married | 34.4% | 35.8% | 33.8% |
| Divorced | 12.0% | 8.7% | 10.8% |
| Widowed | 5.4% | 4.2% | 5.6% |
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| Household Size | 2.45 | 2.78 | 2.60 |
| Households | 9,083 | 14,294 | 124,010,992 |
| Family Households | 5,949 | 10,738 | 80,755,759 |
| Married couple, w/children | 29.3% | 30.9% | 30.5% |
| Married couple, no children | 39.2% | 37.4% | 42.9% |
| Non Family Households | 3,134 | 3,556 | 43,255,233 |
| Single householder, w/children | 10.2% | 15.4% | 15.8% |
| Single householder, no children | 21.2% | 16.4% | 10.8% |