| | Norwalk, IA | Delphos, IA | United States |
| Population | 12,592 | 33 | 329,725,481 |
| Female Population | 51.7% | 60.6% | 50.5% |
| Male Population | 48.4% | 39.4% | 49.5% |
| Median Age | 36 | 24.5 | 38.4 |
| space3 | | | |
| Population - 2010 | 9,046 | 8 | 309,327,143 |
| Population - 2000 | 6,884 | 25 | 285,036,114 |
| Population - 1990 | 5,726 | 23 | 251,960,433 |
| Pop. 2000 to Now | 80.8% | -28.0% | 15.6% |
| Pop. 1990 to Now | 117.4% | -21.7% | 30.8% |
| space4 | | | |
| Population Density | 1,101.8 | 148.0 | 93.4 |
| Land Area | 11.4 | 0.2 | 3,531,905.4 |
| Water Area | 0.4 | 0.0 | 264,836.8 |
| space | | | |
| Est. Total Population By Age | | | |
| | Norwalk, IA | Delphos, IA | United States |
| Age 0 to 4 | 6.3% | 24.2% | 5.9% |
| Age 5 to 9 | 7.4% | 12.1% | 6.1% |
| Age 10 to 14 | 11.0% | 0.0% | 6.6% |
| Age 15 to 17 | 4.2% | 0.0% | 3.9% |
| Age 18 to 20 | 1.8% | 0.0% | 4.0% |
| Age 21 to 24 | 3.9% | 15.2% | 5.2% |
| Age 25 to 34 | 13.8% | 24.2% | 13.8% |
| Age 35 to 44 | 14.8% | 0.0% | 12.9% |
| Age 45 to 54 | 12.4% | 15.2% | 12.6% |
| Age 55 to 59 | 6.4% | 0.0% | 6.7% |
| Age 60 to 64 | 6.5% | 0.0% | 6.3% |
| Age 65 to 74 | 6.3% | 3.0% | 9.6% |
| Age 75 to 84 | 3.5% | 6.1% | 4.5% |
| Age 85 and over | 1.8% | 0.0% | 1.9% |
| space1 | | | |
| Race | | | |
| | Norwalk, IA | Delphos, IA | United States |
| White | 94.1% | 100.0% | 59.4% |
| Black | 1.3% | 0.0% | 12.2% |
| Asian | 0.5% | 0.0% | 5.6% |
| Native American | 0.0% | 0.0% | 0.6% |
| Hawaiian, Pacific Islander | 0.0% | 0.0% | 0.2% |
| Other | 0.1% | 0.0% | 0.4% |
| Two or More Races | 2.1% | 0.0% | 3.2% |
| Hispanic | 1.9% | 0.0% | 18.4% |
| space2 | | | |
| Marriage & Family | | | |
| | Norwalk, IA | Delphos, IA | United States |
| Married Population | 58.1% | 76.2% | 49.8% |
| Currently Married | 57.2% | 76.2% | 48.0% |
| Married but Separated | 0.9% | 0.0% | 1.8% |
| Single Population | 41.9% | 23.8% | 50.2% |
| Never Married | 24.0% | 9.5% | 33.8% |
| Divorced | 13.9% | 0.0% | 10.8% |
| Widowed | 3.9% | 14.3% | 5.6% |
| space5 | | | |
| Household Size | 2.59 | 4.13 | 2.60 |
| Households | 4,818 | 8 | 124,010,992 |
| Family Households | 3,200 | 5 | 80,755,759 |
| Married couple, w/children | 45.0% | 60.0% | 30.5% |
| Married couple, no children | 36.1% | 40.0% | 42.9% |
| Non Family Households | 1,618 | 3 | 43,255,233 |
| Single householder, w/children | 15.1% | 0.0% | 15.8% |
| Single householder, no children | 3.8% | 0.0% | 10.8% |