| PEOPLE | Northfield | Aurora | United States |
| Population | 20,007 | 325,078 | 308,035,306 |
| Pop. Density | 2,337 | 2,101 | 87 |
| Pop. Change | 14.22% | 19.51% | 8.07% |
| Median Age | 26.4 | 33.2 | 37.3 |
| Households | 6,272 | 121,901 | 116,716,292 |
| Household Size | 2.48 | 2.66 | 2.58 |
| Male Population | 47.40% | 49.25% | 49.27% |
| Female Population | 52.60% | 50.75% | 50.96% |
| Married Population | 38.36% | 44.54% | 47.02% |
| Single Population | 61.64% | 55.46% | 52.98% |
| ESTIMATED TOTAL POPULATION BY AGE | | | |
| Age 0 to 4 | 5.33% | 8.36% | 6.56% |
| Age 5 to 9 | 5.81% | 7.77% | 6.61% |
| Age 10 to 14 | 5.17% | 7.03% | 6.71% |
| Age 15 to 17 | 3.45% | 4.17% | 4.21% |
| Age 18 to 20 | 10.34% | 2.46% | 2.95% |
| Age 21 to 24 | 18.69% | 6.82% | 7.01% |
| Age 25 to 34 | 8.96% | 16.21% | 13.33% |
| Age 35 to 44 | 10.20% | 14.53% | 13.33% |
| Age 45 to 49 | 11.04% | 13.35% | 14.61% |
| Age 50 to 54 | 11.04% | 13.35% | 14.61% |
| Age 55 to 59 | 8.99% | 10.36% | 11.84% |
| Age 60 to 64 | 8.99% | 10.36% | 11.84% |
| Age 65 to 74 | 5.26% | 5.13% | 7.05% |
| Age 75 to 84 | 4.34% | 2.71% | 4.24% |
| Age 85 and over | 2.41% | 1.10% | 1.78% |
| RACE | | | |
| White | 88.78% | 61.13% | 72.41% |
| Black | 1.28% | 15.75% | 12.61% |
| Asian | 3.45% | 4.95% | 4.75% |
| American Indian | 0.24% | 0.95% | 0.95% |
| Other | 6.23% | 17.22% | 9.28% |
| Hispanic | 0.00% | 5.17% | 16.35% |
| Non-Hispanic | 100.00% | 94.83% | 83.65% |
| FAMILY | | | |
| Married, w/children | 35.76% | 33.23% | 30.42% |
| Married, no children | 43.72% | 35.65% | 42.46% |
| Single, w/children | 14.01% | 18.18% | 14.39% |
| Single, no children | 6.51% | 12.95% | 12.73% |
| Divorced | 6.92% | 13.36% | 10.62% |
| Separated | 4.49% | 5.93% | 4.97% |
| Widowed | 4.82% | 4.79% | 6.14% |
| Now Married | 39.02% | 44.54% | 46.32% |
| Never Married | 44.75% | 31.38% | 31.95% |
