| | Lexington, MA | Pleasanton, CA | United States |
| Population | 34,235 | 79,558 | 329,725,481 |
| Female Population | 51.3% | 50.6% | 50.5% |
| Male Population | 48.7% | 49.4% | 49.5% |
| Median Age | 46.6 | 41.1 | 38.4 |
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| Population - 2010 | 31,512 | 70,363 | 309,327,143 |
| Population - 2000 | 30,355 | 63,654 | 285,036,114 |
| Population - 1990 | 28,974 | 50,553 | 251,960,433 |
| Pop. 2000 to Now | 8.7% | 26.1% | 15.6% |
| Pop. 1990 to Now | 13.9% | 58.7% | 30.8% |
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| Population Density | 2,083.2 | 3,294.7 | 93.4 |
| Land Area | 16.4 | 24.1 | 3,531,905.4 |
| Water Area | 0.2 | 0.1 | 264,836.8 |
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| Est. Total Population By Age | | | |
| | Lexington, MA | Pleasanton, CA | United States |
| Age 0 to 4 | 3.2% | 4.8% | 5.9% |
| Age 5 to 9 | 6.6% | 6.6% | 6.1% |
| Age 10 to 14 | 10.5% | 8.3% | 6.6% |
| Age 15 to 17 | 6.6% | 4.4% | 3.9% |
| Age 18 to 20 | 2.4% | 3.2% | 4.0% |
| Age 21 to 24 | 2.4% | 3.1% | 5.2% |
| Age 25 to 34 | 3.6% | 10.4% | 13.8% |
| Age 35 to 44 | 11.4% | 15.3% | 12.9% |
| Age 45 to 54 | 19.9% | 15.8% | 12.6% |
| Age 55 to 59 | 7.7% | 7.0% | 6.7% |
| Age 60 to 64 | 5.0% | 6.4% | 6.3% |
| Age 65 to 74 | 12.3% | 7.9% | 9.6% |
| Age 75 to 84 | 5.6% | 5.1% | 4.5% |
| Age 85 and over | 3.0% | 1.9% | 1.9% |
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| Race | | | |
| | Lexington, MA | Pleasanton, CA | United States |
| White | 60.1% | 43.5% | 59.4% |
| Black | 1.1% | 1.8% | 12.2% |
| Asian | 31.8% | 38.9% | 5.6% |
| Native American | 0.0% | 0.4% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.5% | 0.2% |
| Other | 0.7% | 0.1% | 0.4% |
| Two or More Races | 4.1% | 4.0% | 3.2% |
| Hispanic | 2.2% | 10.8% | 18.4% |
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| Marriage & Family | | | |
| | Lexington, MA | Pleasanton, CA | United States |
| Married Population | 68.7% | 65.1% | 49.8% |
| Currently Married | 67.9% | 63.7% | 48.0% |
| Married but Separated | 0.8% | 1.4% | 1.8% |
| Single Population | 31.3% | 34.9% | 50.2% |
| Never Married | 21.3% | 24.2% | 33.8% |
| Divorced | 5.7% | 6.8% | 10.8% |
| Widowed | 4.3% | 4.0% | 5.6% |
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| Household Size | 2.75 | 2.86 | 2.60 |
| Households | 12,301 | 27,733 | 124,010,992 |
| Family Households | 9,753 | 21,582 | 80,755,759 |
| Married couple, w/children | 47.9% | 43.7% | 30.5% |
| Married couple, no children | 41.7% | 43.3% | 42.9% |
| Non Family Households | 2,548 | 6,151 | 43,255,233 |
| Single householder, w/children | 7.2% | 6.7% | 15.8% |
| Single householder, no children | 3.2% | 6.2% | 10.8% |