| | Arthur, ND | Fargo, ND | United States |
| Population | 299 | 124,979 | 329,725,481 |
| Female Population | 46.5% | 49.8% | 50.5% |
| Male Population | 53.5% | 50.3% | 49.5% |
| Median Age | 44.6 | 31.5 | 38.4 |
| space3 | | | |
| Population - 2010 | 337 | 106,024 | 309,327,143 |
| Population - 2000 | 402 | 90,599 | 285,036,114 |
| Population - 1990 | 400 | 74,111 | 251,960,433 |
| Pop. 2000 to Now | -16.9% | 38.2% | 15.6% |
| Pop. 1990 to Now | -16.5% | 69.0% | 30.8% |
| space4 | | | |
| Population Density | 195.4 | 2,512.5 | 93.4 |
| Land Area | 1.5 | 49.7 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Arthur, ND | Fargo, ND | United States |
| Age 0 to 4 | 5.4% | 6.4% | 5.9% |
| Age 5 to 9 | 7.4% | 5.6% | 6.1% |
| Age 10 to 14 | 6.7% | 5.2% | 6.6% |
| Age 15 to 17 | 5.7% | 3.0% | 3.9% |
| Age 18 to 20 | 1.7% | 6.6% | 4.0% |
| Age 21 to 24 | 3.3% | 10.2% | 5.2% |
| Age 25 to 34 | 6.7% | 18.2% | 13.8% |
| Age 35 to 44 | 14.0% | 12.7% | 12.9% |
| Age 45 to 54 | 15.4% | 9.3% | 12.6% |
| Age 55 to 59 | 7.7% | 4.9% | 6.7% |
| Age 60 to 64 | 3.7% | 5.4% | 6.3% |
| Age 65 to 74 | 7.7% | 7.4% | 9.6% |
| Age 75 to 84 | 11.0% | 3.6% | 4.5% |
| Age 85 and over | 3.7% | 1.7% | 1.9% |
| space1 | | | |
| Race | | | |
| | Arthur, ND | Fargo, ND | United States |
| White | 97.3% | 80.9% | 59.4% |
| Black | 1.0% | 8.0% | 12.2% |
| Asian | 0.0% | 4.0% | 5.6% |
| Native American | 1.0% | 1.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.2% | 0.4% |
| Two or More Races | 0.0% | 2.5% | 3.2% |
| Hispanic | 0.7% | 3.2% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Arthur, ND | Fargo, ND | United States |
| Married Population | 61.0% | 44.4% | 49.8% |
| Currently Married | 60.6% | 43.4% | 48.0% |
| Married but Separated | 0.4% | 1.0% | 1.8% |
| Single Population | 39.0% | 55.6% | 50.2% |
| Never Married | 27.8% | 43.0% | 33.8% |
| Divorced | 4.6% | 8.6% | 10.8% |
| Widowed | 6.6% | 3.9% | 5.6% |
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| Household Size | 2.45 | 2.15 | 2.60 |
| Households | 112 | 55,857 | 124,010,992 |
| Family Households | 74 | 27,788 | 80,755,759 |
| Married couple, w/children | 39.2% | 32.3% | 30.5% |
| Married couple, no children | 55.4% | 44.5% | 42.9% |
| Non Family Households | 38 | 28,069 | 43,255,233 |
| Single householder, w/children | 2.7% | 15.6% | 15.8% |
| Single householder, no children | 2.7% | 7.5% | 10.8% |