Benton County Population 2018
Benton County's estimated population is 25,642 with a growth rate of 0.00% in the past year according to the most recent United States census data. Benton County is the 24th largest county in Iowa.
| Year | Population | Growth | Growth Rate |
| 2017 | 25,642 | 1 | 0.00% |
| 2016 | 25,641 | 30 | 0.12% |
| 2015 | 25,611 | -19 | -0.07% |
| 2014 | 25,630 | -76 | -0.30% |
| 2013 | 25,706 | -130 | -0.50% |
| 2012 | 25,836 | -243 | -0.93% |
| 2011 | 26,079 | 30 | 0.12% |
| 2010 | 26,049 | 3,620 | 16.14% |
| 1990 | 22,429 | -1,220 | -5.16% |
| 1980 | 23,649 | 764 | 3.34% |
| 1970 | 22,885 | -537 | -2.29% |
| 1960 | 23,422 | 766 | 3.38% |
| 1950 | 22,656 | -223 | -0.97% |
| 1940 | 22,879 | 28 | 0.12% |
| 1930 | 22,851 | -1,229 | -5.10% |
| 1920 | 24,080 | 924 | 3.99% |
| 1910 | 23,156 | -2,021 | -8.03% |
| 1900 | 25,177 | 999 | 4.13% |
| 1890 | 24,178 | -710 | -2.85% |
| 1880 | 24,888 | 2,434 | 10.84% |
| 1870 | 22,454 | 13,958 | 164.29% |
| 1860 | 8,496 | 7,824 | 1164.29% |
| 1850 | 672 | 0.00% |