| | Lame Deer, MT | Forsyth, MT | United States |
| Population | 2,231 | 1,562 | 329,725,481 |
| Female Population | 50.4% | 47.0% | 50.5% |
| Male Population | 49.6% | 53.0% | 49.5% |
| Median Age | 20.8 | 36.5 | 38.4 |
| space3 | | | |
| Population - 2010 | 2,115 | 1,860 | 309,327,143 |
| Population - 2000 | 2,018 | 1,944 | 285,036,114 |
| Population - 1990 | 1,918 | 2,178 | 251,960,433 |
| Pop. 2000 to Now | 2.4% | -9.9% | 15.6% |
| Pop. 1990 to Now | 7.8% | -19.6% | 30.8% |
| space4 | | | |
| Population Density | 40.1 | 1,355.9 | 93.4 |
| Land Area | 55.6 | 1.2 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Lame Deer, MT | Forsyth, MT | United States |
| Age 0 to 4 | 12.5% | 7.2% | 5.9% |
| Age 5 to 9 | 14.1% | 4.8% | 6.1% |
| Age 10 to 14 | 10.5% | 5.4% | 6.6% |
| Age 15 to 17 | 6.7% | 1.6% | 3.9% |
| Age 18 to 20 | 6.6% | 7.0% | 4.0% |
| Age 21 to 24 | 8.3% | 6.4% | 5.2% |
| Age 25 to 34 | 10.8% | 16.6% | 13.8% |
| Age 35 to 44 | 11.2% | 4.8% | 12.9% |
| Age 45 to 54 | 6.6% | 5.7% | 12.6% |
| Age 55 to 59 | 3.5% | 4.8% | 6.7% |
| Age 60 to 64 | 3.3% | 7.0% | 6.3% |
| Age 65 to 74 | 4.6% | 19.4% | 9.6% |
| Age 75 to 84 | 1.2% | 8.9% | 4.5% |
| Age 85 and over | 0.0% | 0.3% | 1.9% |
| space1 | | | |
| Race | | | |
| | Lame Deer, MT | Forsyth, MT | United States |
| White | 1.0% | 78.2% | 59.4% |
| Black | 0.4% | 0.0% | 12.2% |
| Asian | 0.0% | 1.5% | 5.6% |
| Native American | 96.4% | 1.5% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 0.7% | 12.8% | 3.2% |
| Hispanic | 1.5% | 6.1% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Lame Deer, MT | Forsyth, MT | United States |
| Married Population | 23.6% | 53.5% | 49.8% |
| Currently Married | 22.0% | 53.1% | 48.0% |
| Married but Separated | 1.6% | 0.4% | 1.8% |
| Single Population | 76.4% | 46.5% | 50.2% |
| Never Married | 62.5% | 33.6% | 33.8% |
| Divorced | 10.8% | 8.9% | 10.8% |
| Widowed | 3.1% | 4.0% | 5.6% |
| space5 | | | |
| Household Size | 5.08 | 2.46 | 2.60 |
| Households | 437 | 608 | 124,010,992 |
| Family Households | 354 | 371 | 80,755,759 |
| Married couple, w/children | 28.8% | 19.7% | 30.5% |
| Married couple, no children | 11.9% | 64.7% | 42.9% |
| Non Family Households | 83 | 237 | 43,255,233 |
| Single householder, w/children | 40.7% | 12.4% | 15.8% |
| Single householder, no children | 18.6% | 3.2% | 10.8% |