| | Gaffney, SC | Monticello, MN | United States |
| Population | 12,560 | 14,235 | 329,725,481 |
| Female Population | 51.8% | 52.7% | 50.5% |
| Male Population | 48.2% | 47.4% | 49.5% |
| Median Age | 34.7 | 34.8 | 38.4 |
| space3 | | | |
| Population - 2010 | 12,574 | 12,832 | 309,327,143 |
| Population - 2000 | 12,968 | 7,868 | 285,036,114 |
| Population - 1990 | 13,145 | 4,941 | 251,960,433 |
| Pop. 2000 to Now | -2.1% | 76.6% | 15.6% |
| Pop. 1990 to Now | -3.4% | 181.2% | 30.8% |
| space4 | | | |
| Population Density | 1,504.6 | 1,625.9 | 93.4 |
| Land Area | 8.3 | 8.8 | 3,531,905.4 |
| Water Area | 0.0 | 0.1 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Gaffney, SC | Monticello, MN | United States |
| Age 0 to 4 | 8.0% | 8.5% | 5.9% |
| Age 5 to 9 | 6.2% | 5.7% | 6.1% |
| Age 10 to 14 | 5.1% | 8.6% | 6.6% |
| Age 15 to 17 | 3.1% | 5.0% | 3.9% |
| Age 18 to 20 | 8.5% | 2.8% | 4.0% |
| Age 21 to 24 | 5.8% | 6.4% | 5.2% |
| Age 25 to 34 | 13.4% | 13.6% | 13.8% |
| Age 35 to 44 | 13.3% | 15.6% | 12.9% |
| Age 45 to 54 | 10.7% | 12.2% | 12.6% |
| Age 55 to 59 | 3.3% | 7.6% | 6.7% |
| Age 60 to 64 | 5.9% | 4.3% | 6.3% |
| Age 65 to 74 | 9.2% | 6.0% | 9.6% |
| Age 75 to 84 | 5.4% | 2.6% | 4.5% |
| Age 85 and over | 1.9% | 1.3% | 1.9% |
| space1 | | | |
| Race | | | |
| | Gaffney, SC | Monticello, MN | United States |
| White | 46.3% | 88.1% | 59.4% |
| Black | 42.2% | 0.4% | 12.2% |
| Asian | 0.0% | 0.8% | 5.6% |
| Native American | 0.3% | 0.5% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 2.3% | 0.0% | 0.4% |
| Two or More Races | 4.4% | 1.7% | 3.2% |
| Hispanic | 4.4% | 8.5% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Gaffney, SC | Monticello, MN | United States |
| Married Population | 33.8% | 50.3% | 49.8% |
| Currently Married | 31.2% | 49.4% | 48.0% |
| Married but Separated | 2.5% | 0.9% | 1.8% |
| Single Population | 66.2% | 49.7% | 50.2% |
| Never Married | 46.1% | 31.5% | 33.8% |
| Divorced | 12.8% | 13.7% | 10.8% |
| Widowed | 7.2% | 4.5% | 5.6% |
| space5 | | | |
| Household Size | 2.48 | 2.62 | 2.60 |
| Households | 4,766 | 5,379 | 124,010,992 |
| Family Households | 2,395 | 3,308 | 80,755,759 |
| Married couple, w/children | 19.7% | 43.9% | 30.5% |
| Married couple, no children | 35.7% | 35.0% | 42.9% |
| Non Family Households | 2,371 | 2,071 | 43,255,233 |
| Single householder, w/children | 22.5% | 16.9% | 15.8% |
| Single householder, no children | 22.0% | 4.2% | 10.8% |