| | Lexington, SC | Seneca, SC | United States |
| Population | 23,068 | 8,734 | 329,725,481 |
| Female Population | 50.4% | 53.0% | 50.5% |
| Male Population | 49.6% | 47.0% | 49.5% |
| Median Age | 37.7 | 39.6 | 38.4 |
| space3 | | | |
| Population - 2010 | 18,714 | 8,111 | 309,327,143 |
| Population - 2000 | 9,793 | 7,652 | 285,036,114 |
| Population - 1990 | 3,289 | 7,726 | 251,960,433 |
| Pop. 2000 to Now | 132.0% | 11.9% | 15.6% |
| Pop. 1990 to Now | 590.7% | 10.9% | 30.8% |
| space4 | | | |
| Population Density | 2,020.9 | 1,110.5 | 93.4 |
| Land Area | 11.4 | 7.9 | 3,531,905.4 |
| Water Area | 0.1 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Lexington, SC | Seneca, SC | United States |
| Age 0 to 4 | 7.7% | 8.3% | 5.9% |
| Age 5 to 9 | 7.0% | 3.7% | 6.1% |
| Age 10 to 14 | 6.5% | 4.5% | 6.6% |
| Age 15 to 17 | 3.4% | 2.5% | 3.9% |
| Age 18 to 20 | 3.1% | 3.9% | 4.0% |
| Age 21 to 24 | 3.3% | 1.8% | 5.2% |
| Age 25 to 34 | 14.9% | 19.6% | 13.8% |
| Age 35 to 44 | 17.2% | 11.4% | 12.9% |
| Age 45 to 54 | 11.2% | 9.3% | 12.6% |
| Age 55 to 59 | 5.7% | 6.6% | 6.7% |
| Age 60 to 64 | 6.0% | 8.4% | 6.3% |
| Age 65 to 74 | 6.6% | 10.6% | 9.6% |
| Age 75 to 84 | 4.5% | 7.1% | 4.5% |
| Age 85 and over | 2.7% | 2.3% | 1.9% |
| space1 | | | |
| Race | | | |
| | Lexington, SC | Seneca, SC | United States |
| White | 76.1% | 69.3% | 59.4% |
| Black | 10.5% | 20.7% | 12.2% |
| Asian | 5.3% | 0.2% | 5.6% |
| Native American | 0.1% | 0.3% | 0.6% |
| Hawaiian, Pacific Islander | 0.7% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 2.0% | 1.6% | 3.2% |
| Hispanic | 5.3% | 7.8% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Lexington, SC | Seneca, SC | United States |
| Married Population | 54.5% | 45.0% | 49.8% |
| Currently Married | 52.1% | 41.8% | 48.0% |
| Married but Separated | 2.3% | 3.2% | 1.8% |
| Single Population | 45.5% | 55.0% | 50.2% |
| Never Married | 28.2% | 34.2% | 33.8% |
| Divorced | 11.5% | 13.2% | 10.8% |
| Widowed | 5.8% | 7.6% | 5.6% |
| space5 | | | |
| Household Size | 2.44 | 2.36 | 2.60 |
| Households | 8,923 | 3,678 | 124,010,992 |
| Family Households | 5,565 | 2,025 | 80,755,759 |
| Married couple, w/children | 43.0% | 21.3% | 30.5% |
| Married couple, no children | 36.6% | 51.6% | 42.9% |
| Non Family Households | 3,358 | 1,653 | 43,255,233 |
| Single householder, w/children | 15.8% | 16.4% | 15.8% |
| Single householder, no children | 4.7% | 10.7% | 10.8% |