| | Richfield, PA | Mifflinburg, PA | United States |
| Population | 387 | 3,438 | 329,725,481 |
| Female Population | 53.0% | 45.8% | 50.5% |
| Male Population | 47.0% | 54.2% | 49.5% |
| Median Age | 59.6 | 39 | 38.4 |
| space3 | | | |
| Population - 2010 | 613 | 3,518 | 309,327,143 |
| Population - 2000 | 459 | 3,594 | 285,036,114 |
| Population - 1990 | 286 | 3,480 | 251,960,433 |
| Pop. 2000 to Now | 19.0% | -4.2% | 15.6% |
| Pop. 1990 to Now | 90.9% | -1.0% | 30.8% |
| space4 | | | |
| Population Density | 332.8 | 1,905.8 | 93.4 |
| Land Area | 1.2 | 1.8 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Richfield, PA | Mifflinburg, PA | United States |
| Age 0 to 4 | 5.4% | 5.5% | 5.9% |
| Age 5 to 9 | 5.9% | 6.7% | 6.1% |
| Age 10 to 14 | 1.3% | 5.1% | 6.6% |
| Age 15 to 17 | 3.6% | 3.4% | 3.9% |
| Age 18 to 20 | 1.8% | 2.7% | 4.0% |
| Age 21 to 24 | 1.6% | 5.5% | 5.2% |
| Age 25 to 34 | 10.1% | 16.2% | 13.8% |
| Age 35 to 44 | 9.8% | 8.5% | 12.9% |
| Age 45 to 54 | 3.1% | 11.1% | 12.6% |
| Age 55 to 59 | 8.0% | 8.4% | 6.7% |
| Age 60 to 64 | 5.7% | 5.9% | 6.3% |
| Age 65 to 74 | 18.9% | 14.5% | 9.6% |
| Age 75 to 84 | 12.7% | 3.9% | 4.5% |
| Age 85 and over | 12.1% | 2.6% | 1.9% |
| space1 | | | |
| Race | | | |
| | Richfield, PA | Mifflinburg, PA | United States |
| White | 100.0% | 98.0% | 59.4% |
| Black | 0.0% | 0.5% | 12.2% |
| Asian | 0.0% | 0.0% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 0.0% | 0.4% | 3.2% |
| Hispanic | 0.0% | 1.2% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Richfield, PA | Mifflinburg, PA | United States |
| Married Population | 50.6% | 53.7% | 49.8% |
| Currently Married | 49.4% | 52.2% | 48.0% |
| Married but Separated | 1.2% | 1.5% | 1.8% |
| Single Population | 49.4% | 46.3% | 50.2% |
| Never Married | 15.4% | 26.9% | 33.8% |
| Divorced | 12.1% | 10.4% | 10.8% |
| Widowed | 21.9% | 9.0% | 5.6% |
| space5 | | | |
| Household Size | 1.81 | 2.41 | 2.60 |
| Households | 193 | 1,427 | 124,010,992 |
| Family Households | 79 | 847 | 80,755,759 |
| Married couple, w/children | 31.6% | 22.8% | 30.5% |
| Married couple, no children | 58.2% | 58.0% | 42.9% |
| Non Family Households | 114 | 580 | 43,255,233 |
| Single householder, w/children | 6.3% | 17.1% | 15.8% |
| Single householder, no children | 3.8% | 2.1% | 10.8% |