| | Trego, MT | St. Maries, ID | United States |
| Population | 824 | 2,951 | 329,725,481 |
| Female Population | 46.5% | 50.9% | 50.5% |
| Male Population | 53.5% | 49.1% | 49.5% |
| Median Age | 39.4 | 39.3 | 38.4 |
| space3 | | | |
| Population - 2010 | 592 | 2,500 | 309,327,143 |
| Population - 2000 | 395 | 2,652 | 285,036,114 |
| Population - 1990 | 280 | 2,442 | 251,960,433 |
| Pop. 2000 to Now | 49.1% | -7.1% | 15.6% |
| Pop. 1990 to Now | 110.4% | 0.9% | 30.8% |
| space4 | | | |
| Population Density | 16.1 | 2,486.1 | 93.4 |
| Land Area | 51.2 | 1.2 | 3,531,905.4 |
| Water Area | 0.9 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Trego, MT | St. Maries, ID | United States |
| Age 0 to 4 | 1.6% | 8.6% | 5.9% |
| Age 5 to 9 | 7.9% | 5.3% | 6.1% |
| Age 10 to 14 | 12.6% | 6.9% | 6.6% |
| Age 15 to 17 | 3.4% | 3.6% | 3.9% |
| Age 18 to 20 | 2.5% | 1.6% | 4.0% |
| Age 21 to 24 | 1.1% | 7.5% | 5.2% |
| Age 25 to 34 | 7.0% | 10.5% | 13.8% |
| Age 35 to 44 | 20.0% | 11.5% | 12.9% |
| Age 45 to 54 | 5.1% | 12.6% | 12.6% |
| Age 55 to 59 | 6.7% | 9.3% | 6.7% |
| Age 60 to 64 | 10.8% | 6.6% | 6.3% |
| Age 65 to 74 | 16.6% | 6.6% | 9.6% |
| Age 75 to 84 | 3.3% | 6.1% | 4.5% |
| Age 85 and over | 1.3% | 3.2% | 1.9% |
| space1 | | | |
| Race | | | |
| | Trego, MT | St. Maries, ID | United States |
| White | 93.8% | 94.3% | 59.4% |
| Black | 1.0% | 0.0% | 12.2% |
| Asian | 0.0% | 0.3% | 5.6% |
| Native American | 0.0% | 0.5% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.1% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 2.5% | 2.1% | 3.2% |
| Hispanic | 2.7% | 2.6% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Trego, MT | St. Maries, ID | United States |
| Married Population | 65.9% | 48.2% | 49.8% |
| Currently Married | 65.9% | 46.4% | 48.0% |
| Married but Separated | 0.0% | 1.8% | 1.8% |
| Single Population | 34.1% | 51.8% | 50.2% |
| Never Married | 21.0% | 24.1% | 33.8% |
| Divorced | 6.1% | 20.7% | 10.8% |
| Widowed | 7.0% | 7.0% | 5.6% |
| space5 | | | |
| Household Size | 2.70 | 2.54 | 2.60 |
| Households | 301 | 1,135 | 124,010,992 |
| Family Households | 227 | 668 | 80,755,759 |
| Married couple, w/children | 31.3% | 41.0% | 30.5% |
| Married couple, no children | 60.4% | 34.3% | 42.9% |
| Non Family Households | 74 | 467 | 43,255,233 |
| Single householder, w/children | 3.5% | 14.2% | 15.8% |
| Single householder, no children | 4.8% | 10.5% | 10.8% |