Putnam County Population 2018
Putnam County's estimated population is 5,727 with a growth rate of 0.17% in the past year according to the most recent United States census data. Putnam County is the 95th largest county in Illinois.
| Year | Population | Growth | Growth Rate |
| 2017 | 5,727 | 10 | 0.17% |
| 2016 | 5,717 | -10 | -0.17% |
| 2015 | 5,727 | -103 | -1.77% |
| 2014 | 5,830 | -22 | -0.38% |
| 2013 | 5,852 | -57 | -0.96% |
| 2012 | 5,909 | -66 | -1.10% |
| 2011 | 5,975 | -37 | -0.62% |
| 2010 | 6,012 | 282 | 4.92% |
| 1990 | 5,730 | -355 | -5.83% |
| 1980 | 6,085 | 1,078 | 21.53% |
| 1970 | 5,007 | 437 | 9.56% |
| 1960 | 4,570 | -176 | -3.71% |
| 1950 | 4,746 | -543 | -10.27% |
| 1940 | 5,289 | 54 | 1.03% |
| 1930 | 5,235 | -2,344 | -30.93% |
| 1920 | 7,579 | 18 | 0.24% |
| 1910 | 7,561 | 2,815 | 59.31% |
| 1900 | 4,746 | 16 | 0.34% |
| 1890 | 4,730 | -824 | -14.84% |
| 1880 | 5,554 | -726 | -11.56% |
| 1870 | 6,280 | 693 | 12.40% |
| 1860 | 5,587 | 1,663 | 42.38% |
| 1850 | 3,924 | 1,793 | 84.14% |
| 1840 | 2,131 | 821 | 62.67% |
| 1830 | 1,310 | 0.00% |