Cowley County Population 2018
Cowley County's estimated population is 35,361 with a growth rate of -0.73% in the past year according to the most recent United States census data. Cowley County is the 13th largest county in Kansas.
| Year | Population | Growth | Growth Rate |
| 2017 | 35,361 | -260 | -0.73% |
| 2016 | 35,621 | -69 | -0.19% |
| 2015 | 35,690 | -154 | -0.43% |
| 2014 | 35,844 | -298 | -0.82% |
| 2013 | 36,142 | -109 | -0.30% |
| 2012 | 36,251 | 16 | 0.04% |
| 2011 | 36,235 | -73 | -0.20% |
| 2010 | 36,308 | -607 | -1.64% |
| 1990 | 36,915 | 91 | 0.25% |
| 1980 | 36,824 | 1,812 | 5.18% |
| 1970 | 35,012 | -2,849 | -7.52% |
| 1960 | 37,861 | 956 | 2.59% |
| 1950 | 36,905 | -1,234 | -3.24% |
| 1940 | 38,139 | -2,764 | -6.76% |
| 1930 | 40,903 | 5,748 | 16.35% |
| 1920 | 35,155 | 3,365 | 10.59% |
| 1910 | 31,790 | 1,634 | 5.42% |
| 1900 | 30,156 | -4,322 | -12.54% |
| 1890 | 34,478 | 12,940 | 60.08% |
| 1880 | 21,538 | 20,363 | 1733.02% |
| 1870 | 1,175 | 1,017 | 643.67% |
| 1860 | 158 | 0.00% |