| | Lancaster, SC | Gaffney, SC | United States |
| Population | 8,489 | 12,560 | 329,725,481 |
| Female Population | 52.7% | 51.8% | 50.5% |
| Male Population | 47.4% | 48.2% | 49.5% |
| Median Age | 37 | 34.7 | 38.4 |
| space3 | | | |
| Population - 2010 | 8,736 | 12,574 | 309,327,143 |
| Population - 2000 | 8,177 | 12,968 | 285,036,114 |
| Population - 1990 | 8,914 | 13,145 | 251,960,433 |
| Pop. 2000 to Now | 12.0% | -2.1% | 15.6% |
| Pop. 1990 to Now | 2.7% | -3.4% | 30.8% |
| space4 | | | |
| Population Density | 1,318.0 | 1,504.6 | 93.4 |
| Land Area | 6.4 | 8.3 | 3,531,905.4 |
| Water Area | 0.1 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Lancaster, SC | Gaffney, SC | United States |
| Age 0 to 4 | 6.3% | 8.0% | 5.9% |
| Age 5 to 9 | 7.5% | 6.2% | 6.1% |
| Age 10 to 14 | 8.6% | 5.1% | 6.6% |
| Age 15 to 17 | 4.7% | 3.1% | 3.9% |
| Age 18 to 20 | 3.7% | 8.5% | 4.0% |
| Age 21 to 24 | 3.2% | 5.8% | 5.2% |
| Age 25 to 34 | 13.1% | 13.4% | 13.8% |
| Age 35 to 44 | 13.5% | 13.3% | 12.9% |
| Age 45 to 54 | 10.0% | 10.7% | 12.6% |
| Age 55 to 59 | 5.3% | 3.3% | 6.7% |
| Age 60 to 64 | 6.0% | 5.9% | 6.3% |
| Age 65 to 74 | 10.4% | 9.2% | 9.6% |
| Age 75 to 84 | 4.8% | 5.4% | 4.5% |
| Age 85 and over | 2.8% | 1.9% | 1.9% |
| space1 | | | |
| Race | | | |
| | Lancaster, SC | Gaffney, SC | United States |
| White | 36.3% | 46.3% | 59.4% |
| Black | 51.5% | 42.2% | 12.2% |
| Asian | 0.3% | 0.0% | 5.6% |
| Native American | 0.1% | 0.3% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 2.3% | 0.4% |
| Two or More Races | 3.0% | 4.4% | 3.2% |
| Hispanic | 8.8% | 4.4% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Lancaster, SC | Gaffney, SC | United States |
| Married Population | 39.3% | 33.8% | 49.8% |
| Currently Married | 36.3% | 31.2% | 48.0% |
| Married but Separated | 3.0% | 2.5% | 1.8% |
| Single Population | 60.7% | 66.2% | 50.2% |
| Never Married | 41.5% | 46.1% | 33.8% |
| Divorced | 11.2% | 12.8% | 10.8% |
| Widowed | 7.9% | 7.2% | 5.6% |
| space5 | | | |
| Household Size | 2.50 | 2.48 | 2.60 |
| Households | 3,353 | 4,766 | 124,010,992 |
| Family Households | 2,114 | 2,395 | 80,755,759 |
| Married couple, w/children | 14.1% | 19.7% | 30.5% |
| Married couple, no children | 36.4% | 35.7% | 42.9% |
| Non Family Households | 1,239 | 2,371 | 43,255,233 |
| Single householder, w/children | 35.1% | 22.5% | 15.8% |
| Single householder, no children | 14.3% | 22.0% | 10.8% |