| | McArthur, CA | Ferndale, CA | United States |
| Population | 418 | 1,481 | 329,725,481 |
| Female Population | 58.6% | 48.2% | 50.5% |
| Male Population | 41.4% | 51.8% | 49.5% |
| Median Age | 41.3 | 57.2 | 38.4 |
| space3 | | | |
| Population - 2010 | 215 | 1,370 | 309,327,143 |
| Population - 2000 | 365 | 1,382 | 285,036,114 |
| Population - 1990 | 427 | 1,331 | 251,960,433 |
| Pop. 2000 to Now | 4.4% | -1.5% | 15.6% |
| Pop. 1990 to Now | -10.8% | 2.3% | 30.8% |
| space4 | | | |
| Population Density | 417.6 | 1,442.1 | 93.4 |
| Land Area | 1.0 | 1.0 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | McArthur, CA | Ferndale, CA | United States |
| Age 0 to 4 | 5.0% | 3.1% | 5.9% |
| Age 5 to 9 | 4.5% | 4.1% | 6.1% |
| Age 10 to 14 | 19.4% | 5.6% | 6.6% |
| Age 15 to 17 | 7.2% | 3.0% | 3.9% |
| Age 18 to 20 | 7.9% | 3.6% | 4.0% |
| Age 21 to 24 | 0.0% | 6.7% | 5.2% |
| Age 25 to 34 | 0.0% | 5.3% | 13.8% |
| Age 35 to 44 | 17.9% | 9.9% | 12.9% |
| Age 45 to 54 | 18.9% | 6.8% | 12.6% |
| Age 55 to 59 | 0.0% | 7.4% | 6.7% |
| Age 60 to 64 | 6.5% | 11.1% | 6.3% |
| Age 65 to 74 | 5.3% | 20.8% | 9.6% |
| Age 75 to 84 | 7.4% | 5.6% | 4.5% |
| Age 85 and over | 0.0% | 7.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | McArthur, CA | Ferndale, CA | United States |
| White | 40.7% | 81.7% | 59.4% |
| Black | 0.0% | 0.0% | 12.2% |
| Asian | 0.0% | 3.7% | 5.6% |
| Native American | 0.0% | 0.5% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 24.2% | 4.9% | 3.2% |
| Hispanic | 35.2% | 9.2% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | McArthur, CA | Ferndale, CA | United States |
| Married Population | 49.2% | 48.9% | 49.8% |
| Currently Married | 49.2% | 46.5% | 48.0% |
| Married but Separated | 0.0% | 2.4% | 1.8% |
| Single Population | 50.8% | 51.1% | 50.2% |
| Never Married | 38.0% | 25.6% | 33.8% |
| Divorced | 2.4% | 16.2% | 10.8% |
| Widowed | 10.4% | 9.3% | 5.6% |
| space5 | | | |
| Household Size | 3.01 | 2.46 | 2.60 |
| Households | 139 | 602 | 124,010,992 |
| Family Households | 116 | 398 | 80,755,759 |
| Married couple, w/children | 23.3% | 20.1% | 30.5% |
| Married couple, no children | 39.7% | 49.7% | 42.9% |
| Non Family Households | 23 | 204 | 43,255,233 |
| Single householder, w/children | 30.2% | 8.0% | 15.8% |
| Single householder, no children | 6.9% | 22.1% | 10.8% |