| | Seeley Lake, MT | Montana City, MT | United States |
| Population | 1,566 | 2,735 | 329,725,481 |
| Female Population | 42.7% | 49.6% | 50.5% |
| Male Population | 57.3% | 50.4% | 49.5% |
| Median Age | 59.1 | 45.5 | 38.4 |
| space3 | | | |
| Population - 2010 | 1,374 | 2,505 | 309,327,143 |
| Population - 2000 | 1,436 | 2,094 | 285,036,114 |
| Population - 1990 | 1,022 | 1,663 | 251,960,433 |
| Pop. 2000 to Now | -33.5% | 41.3% | 15.6% |
| Pop. 1990 to Now | -6.6% | 77.9% | 30.8% |
| space4 | | | |
| Population Density | 127.7 | 80.2 | 93.4 |
| Land Area | 12.3 | 34.1 | 3,531,905.4 |
| Water Area | 0.2 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Seeley Lake, MT | Montana City, MT | United States |
| Age 0 to 4 | 3.4% | 3.9% | 5.9% |
| Age 5 to 9 | 1.4% | 5.7% | 6.1% |
| Age 10 to 14 | 0.6% | 8.8% | 6.6% |
| Age 15 to 17 | 3.7% | 7.1% | 3.9% |
| Age 18 to 20 | 0.0% | 1.8% | 4.0% |
| Age 21 to 24 | 5.0% | 2.3% | 5.2% |
| Age 25 to 34 | 11.4% | 5.7% | 13.8% |
| Age 35 to 44 | 4.6% | 14.4% | 12.9% |
| Age 45 to 54 | 12.7% | 16.9% | 12.6% |
| Age 55 to 59 | 8.7% | 7.9% | 6.7% |
| Age 60 to 64 | 8.6% | 9.1% | 6.3% |
| Age 65 to 74 | 23.2% | 12.1% | 9.6% |
| Age 75 to 84 | 9.5% | 3.4% | 4.5% |
| Age 85 and over | 7.0% | 0.9% | 1.9% |
| space1 | | | |
| Race | | | |
| | Seeley Lake, MT | Montana City, MT | United States |
| White | 89.8% | 94.5% | 59.4% |
| Black | 0.0% | 0.9% | 12.2% |
| Asian | 4.3% | 0.0% | 5.6% |
| Native American | 0.0% | 0.4% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 2.1% | 2.2% | 3.2% |
| Hispanic | 3.8% | 2.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Seeley Lake, MT | Montana City, MT | United States |
| Married Population | 55.5% | 73.9% | 49.8% |
| Currently Married | 53.9% | 71.4% | 48.0% |
| Married but Separated | 1.6% | 2.5% | 1.8% |
| Single Population | 44.5% | 26.1% | 50.2% |
| Never Married | 16.3% | 17.7% | 33.8% |
| Divorced | 11.4% | 5.6% | 10.8% |
| Widowed | 16.8% | 2.8% | 5.6% |
| space5 | | | |
| Household Size | 2.01 | 2.79 | 2.60 |
| Households | 780 | 980 | 124,010,992 |
| Family Households | 436 | 830 | 80,755,759 |
| Married couple, w/children | 19.5% | 34.9% | 30.5% |
| Married couple, no children | 69.7% | 56.1% | 42.9% |
| Non Family Households | 344 | 150 | 43,255,233 |
| Single householder, w/children | 3.7% | 8.9% | 15.8% |
| Single householder, no children | 7.1% | 0.0% | 10.8% |