Trego County Population 2018
Trego County's estimated population is 2,884 with a growth rate of 0.73% in the past year according to the most recent United States census data. Trego County is the 84th largest county in Kansas.
| Year | Population | Growth | Growth Rate |
| 2017 | 2,884 | 21 | 0.73% |
| 2016 | 2,863 | -43 | -1.48% |
| 2015 | 2,906 | 11 | 0.38% |
| 2014 | 2,895 | -50 | -1.70% |
| 2013 | 2,945 | 4 | 0.14% |
| 2012 | 2,941 | -12 | -0.41% |
| 2011 | 2,953 | -53 | -1.76% |
| 2010 | 3,006 | -688 | -18.62% |
| 1990 | 3,694 | -471 | -11.31% |
| 1980 | 4,165 | -271 | -6.11% |
| 1970 | 4,436 | -1,037 | -18.95% |
| 1960 | 5,473 | -395 | -6.73% |
| 1950 | 5,868 | 46 | 0.79% |
| 1940 | 5,822 | -648 | -10.02% |
| 1930 | 6,470 | 590 | 10.03% |
| 1920 | 5,880 | 482 | 8.93% |
| 1910 | 5,398 | 2,676 | 98.31% |
| 1900 | 2,722 | 187 | 7.38% |
| 1890 | 2,535 | 0.00% | |
| 1880 | 2,535 | 2,369 | 1427.11% |
| 1870 | 166 | 0.00% |