| | Roundup, MT | Laurel, MT | United States |
| Population | 1,708 | 7,164 | 329,725,481 |
| Female Population | 50.6% | 49.9% | 50.5% |
| Male Population | 49.4% | 50.1% | 49.5% |
| Median Age | 49.8 | 37 | 38.4 |
| space3 | | | |
| Population - 2010 | 1,789 | 6,770 | 309,327,143 |
| Population - 2000 | 1,931 | 6,255 | 285,036,114 |
| Population - 1990 | 1,808 | 5,686 | 251,960,433 |
| Pop. 2000 to Now | -3.5% | 7.4% | 15.6% |
| Pop. 1990 to Now | 3.1% | 18.1% | 30.8% |
| space4 | | | |
| Population Density | 1,321.0 | 3,319.7 | 93.4 |
| Land Area | 1.3 | 2.2 | 3,531,905.4 |
| Water Area | 0.0 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Roundup, MT | Laurel, MT | United States |
| Age 0 to 4 | 2.8% | 4.8% | 5.9% |
| Age 5 to 9 | 4.7% | 9.9% | 6.1% |
| Age 10 to 14 | 8.4% | 6.3% | 6.6% |
| Age 15 to 17 | 4.5% | 2.8% | 3.9% |
| Age 18 to 20 | 4.9% | 2.6% | 4.0% |
| Age 21 to 24 | 2.9% | 6.7% | 5.2% |
| Age 25 to 34 | 8.0% | 13.0% | 13.8% |
| Age 35 to 44 | 10.0% | 10.6% | 12.9% |
| Age 45 to 54 | 11.0% | 14.1% | 12.6% |
| Age 55 to 59 | 6.5% | 8.0% | 6.7% |
| Age 60 to 64 | 12.1% | 6.3% | 6.3% |
| Age 65 to 74 | 13.3% | 7.1% | 9.6% |
| Age 75 to 84 | 9.4% | 6.7% | 4.5% |
| Age 85 and over | 1.5% | 1.2% | 1.9% |
| space1 | | | |
| Race | | | |
| | Roundup, MT | Laurel, MT | United States |
| White | 90.7% | 90.8% | 59.4% |
| Black | 0.0% | 0.3% | 12.2% |
| Asian | 0.0% | 1.7% | 5.6% |
| Native American | 0.9% | 0.5% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.0% | 0.0% | 0.4% |
| Two or More Races | 2.1% | 3.4% | 3.2% |
| Hispanic | 6.3% | 3.3% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Roundup, MT | Laurel, MT | United States |
| Married Population | 51.7% | 50.4% | 49.8% |
| Currently Married | 50.2% | 49.0% | 48.0% |
| Married but Separated | 1.5% | 1.4% | 1.8% |
| Single Population | 48.3% | 49.6% | 50.2% |
| Never Married | 22.1% | 26.4% | 33.8% |
| Divorced | 15.0% | 15.7% | 10.8% |
| Widowed | 11.3% | 7.6% | 5.6% |
| space5 | | | |
| Household Size | 2.03 | 2.40 | 2.60 |
| Households | 831 | 2,958 | 124,010,992 |
| Family Households | 413 | 1,930 | 80,755,759 |
| Married couple, w/children | 27.6% | 25.9% | 30.5% |
| Married couple, no children | 53.8% | 41.0% | 42.9% |
| Non Family Households | 418 | 1,028 | 43,255,233 |
| Single householder, w/children | 9.0% | 17.8% | 15.8% |
| Single householder, no children | 9.7% | 15.3% | 10.8% |