| | Thayer, MO | Pekin, IL | United States |
| Population | 2,116 | 32,398 | 329,725,481 |
| Female Population | 55.0% | 50.9% | 50.5% |
| Male Population | 45.0% | 49.1% | 49.5% |
| Median Age | 40.7 | 41.5 | 38.4 |
| space3 | | | |
| Population - 2010 | 2,220 | 34,041 | 309,327,143 |
| Population - 2000 | 2,201 | 33,857 | 285,036,114 |
| Population - 1990 | 1,996 | 32,254 | 251,960,433 |
| Pop. 2000 to Now | -4.5% | -6.1% | 15.6% |
| Pop. 1990 to Now | 5.4% | -1.4% | 30.8% |
| space4 | | | |
| Population Density | 866.2 | 2,216.0 | 93.4 |
| Land Area | 2.4 | 14.6 | 3,531,905.4 |
| Water Area | 0.0 | 0.8 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Thayer, MO | Pekin, IL | United States |
| Age 0 to 4 | 5.3% | 5.9% | 5.9% |
| Age 5 to 9 | 7.8% | 6.8% | 6.1% |
| Age 10 to 14 | 8.0% | 5.0% | 6.6% |
| Age 15 to 17 | 7.9% | 3.5% | 3.9% |
| Age 18 to 20 | 0.0% | 2.5% | 4.0% |
| Age 21 to 24 | 3.3% | 4.9% | 5.2% |
| Age 25 to 34 | 7.0% | 13.9% | 13.8% |
| Age 35 to 44 | 18.7% | 11.5% | 12.9% |
| Age 45 to 54 | 5.4% | 12.9% | 12.6% |
| Age 55 to 59 | 5.3% | 7.2% | 6.7% |
| Age 60 to 64 | 6.7% | 7.7% | 6.3% |
| Age 65 to 74 | 14.9% | 11.1% | 9.6% |
| Age 75 to 84 | 6.3% | 4.4% | 4.5% |
| Age 85 and over | 3.4% | 2.6% | 1.9% |
| space1 | | | |
| Race | | | |
| | Thayer, MO | Pekin, IL | United States |
| White | 89.1% | 90.8% | 59.4% |
| Black | 0.0% | 3.0% | 12.2% |
| Asian | 0.3% | 0.5% | 5.6% |
| Native American | 0.0% | 0.2% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.1% | 0.2% |
| Other | 0.2% | 0.0% | 0.4% |
| Two or More Races | 8.0% | 2.8% | 3.2% |
| Hispanic | 2.4% | 2.6% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Thayer, MO | Pekin, IL | United States |
| Married Population | 51.6% | 43.2% | 49.8% |
| Currently Married | 49.8% | 41.5% | 48.0% |
| Married but Separated | 1.8% | 1.6% | 1.8% |
| Single Population | 48.4% | 56.8% | 50.2% |
| Never Married | 19.3% | 33.2% | 33.8% |
| Divorced | 17.7% | 15.0% | 10.8% |
| Widowed | 11.4% | 8.7% | 5.6% |
| space5 | | | |
| Household Size | 2.61 | 2.24 | 2.60 |
| Households | 784 | 13,706 | 124,010,992 |
| Family Households | 551 | 7,504 | 80,755,759 |
| Married couple, w/children | 21.4% | 26.0% | 30.5% |
| Married couple, no children | 48.8% | 42.5% | 42.9% |
| Non Family Households | 233 | 6,202 | 43,255,233 |
| Single householder, w/children | 26.1% | 20.1% | 15.8% |
| Single householder, no children | 3.6% | 11.4% | 10.8% |