| | Gardiner, MT | Sheridan, WY | United States |
| Population | 831 | 18,660 | 329,725,481 |
| Female Population | 42.0% | 50.4% | 50.5% |
| Male Population | 58.0% | 49.6% | 49.5% |
| Median Age | 43.9 | 39 | 38.4 |
| space3 | | | |
| Population - 2010 | 850 | 17,487 | 309,327,143 |
| Population - 2000 | 851 | 15,804 | 285,036,114 |
| Population - 1990 | 991 | 13,900 | 251,960,433 |
| Pop. 2000 to Now | 28.7% | 14.5% | 15.6% |
| Pop. 1990 to Now | 10.5% | 30.2% | 30.8% |
| space4 | | | |
| Population Density | 143.5 | 1,472.1 | 93.4 |
| Land Area | 5.8 | 12.7 | 3,531,905.4 |
| Water Area | 0.1 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Gardiner, MT | Sheridan, WY | United States |
| Age 0 to 4 | 2.3% | 5.1% | 5.9% |
| Age 5 to 9 | 5.4% | 6.2% | 6.1% |
| Age 10 to 14 | 3.0% | 8.1% | 6.6% |
| Age 15 to 17 | 0.6% | 3.7% | 3.9% |
| Age 18 to 20 | 1.8% | 5.8% | 4.0% |
| Age 21 to 24 | 8.8% | 3.6% | 5.2% |
| Age 25 to 34 | 12.0% | 12.8% | 13.8% |
| Age 35 to 44 | 16.4% | 11.0% | 12.9% |
| Age 45 to 54 | 21.2% | 10.8% | 12.6% |
| Age 55 to 59 | 10.0% | 6.5% | 6.7% |
| Age 60 to 64 | 4.7% | 6.7% | 6.3% |
| Age 65 to 74 | 10.0% | 10.6% | 9.6% |
| Age 75 to 84 | 3.9% | 5.9% | 4.5% |
| Age 85 and over | 0.0% | 3.1% | 1.9% |
| space1 | | | |
| Race | | | |
| | Gardiner, MT | Sheridan, WY | United States |
| White | 83.4% | 88.8% | 59.4% |
| Black | 1.3% | 0.4% | 12.2% |
| Asian | 0.0% | 1.2% | 5.6% |
| Native American | 0.0% | 1.0% | 0.6% |
| Hawaiian, Pacific Islander | 1.3% | 0.0% | 0.2% |
| Other | 0.0% | 0.3% | 0.4% |
| Two or More Races | 9.3% | 2.1% | 3.2% |
| Hispanic | 4.7% | 6.3% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Gardiner, MT | Sheridan, WY | United States |
| Married Population | 52.2% | 48.5% | 49.8% |
| Currently Married | 50.0% | 46.8% | 48.0% |
| Married but Separated | 2.2% | 1.7% | 1.8% |
| Single Population | 47.8% | 51.5% | 50.2% |
| Never Married | 36.5% | 30.3% | 33.8% |
| Divorced | 9.2% | 14.8% | 10.8% |
| Widowed | 2.2% | 6.4% | 5.6% |
| space5 | | | |
| Household Size | 1.86 | 2.20 | 2.60 |
| Households | 443 | 8,182 | 124,010,992 |
| Family Households | 205 | 4,236 | 80,755,759 |
| Married couple, w/children | 13.2% | 31.2% | 30.5% |
| Married couple, no children | 68.3% | 48.8% | 42.9% |
| Non Family Households | 238 | 3,946 | 43,255,233 |
| Single householder, w/children | 5.4% | 12.7% | 15.8% |
| Single householder, no children | 13.2% | 7.2% | 10.8% |