| |
| Age Group | Male | Female | Montana, 2000, Universe: 001 Total population Universe Population: 902,195 | ||
| Population | Pct | Population | Pct |  | |
| Total | 449,480 | 49.8 | 452,715 | 50.2 | |
| 0- 4 | 28,212 | 3.1 | 26,657 | 3.0 | |
| 5- 9 | 31,822 | 3.5 | 30,141 | 3.3 | |
| 10-14 | 35,657 | 4.0 | 33,641 | 3.7 | |
| 15-19 | 36,789 | 4.1 | 34,521 | 3.8 | |
| 20-24 | 30,345 | 3.4 | 28,034 | 3.1 | |
| 25-29 | 26,389 | 2.9 | 24,715 | 2.7 | |
| 30-34 | 26,060 | 2.9 | 26,115 | 2.9 | |
| 35-39 | 32,877 | 3.6 | 33,703 | 3.7 | |
| 40-44 | 37,065 | 4.1 | 38,296 | 4.2 | |
| 45-49 | 36,907 | 4.1 | 36,491 | 4.0 | |
| 50-54 | 31,615 | 3.5 | 30,075 | 3.3 | |
| 55-59 | 23,864 | 2.6 | 23,310 | 2.6 | |
| 60-64 | 18,936 | 2.1 | 19,009 | 2.1 | |
| 65-69 | 15,810 | 1.8 | 16,731 | 1.9 | |
| 70-74 | 14,045 | 1.6 | 15,933 | 1.8 | |
| 75-79 | 10,941 | 1.2 | 13,762 | 1.5 | |
| 80-84 | 7,264 | 0.8 | 11,126 | 1.2 | |
| 85+ | 4,882 | 0.5 | 10,455 | 1.2 | |