| |
| Age Group | Male | Female | Illinois, 2000, Universe: 001 Total population Universe Population: 12,419,293 | ||
| Population | Pct | Population | Pct |  | |
| Total | 6,080,336 | 49.0 | 6,338,957 | 51.0 | |
| 0- 4 | 447,922 | 3.6 | 428,627 | 3.5 | |
| 5- 9 | 476,180 | 3.8 | 453,678 | 3.7 | |
| 10-14 | 462,915 | 3.7 | 442,182 | 3.6 | |
| 15-19 | 462,538 | 3.7 | 431,464 | 3.5 | |
| 20-24 | 434,984 | 3.5 | 415,859 | 3.3 | |
| 25-29 | 451,178 | 3.6 | 440,581 | 3.5 | |
| 30-34 | 463,257 | 3.7 | 456,658 | 3.7 | |
| 35-39 | 496,442 | 4.0 | 500,444 | 4.0 | |
| 40-44 | 488,627 | 3.9 | 498,357 | 4.0 | |
| 45-49 | 430,143 | 3.5 | 443,669 | 3.6 | |
| 50-54 | 367,435 | 3.0 | 385,495 | 3.1 | |
| 55-59 | 278,223 | 2.2 | 299,524 | 2.4 | |
| 60-64 | 218,881 | 1.8 | 244,005 | 2.0 | |
| 65-69 | 180,927 | 1.5 | 216,516 | 1.7 | |
| 70-74 | 162,794 | 1.3 | 212,010 | 1.7 | |
| 75-79 | 127,172 | 1.0 | 189,776 | 1.5 | |
| 80-84 | 77,733 | 0.6 | 141,066 | 1.1 | |
| 85+ | 52,985 | 0.4 | 139,046 | 1.1 | |