Founded in 1825, Putnam County is one of 102 counties in the state of Illinois. Historically, Putnam County was formed from Fulton County. The city of Hennepin is the county seat. With FIPS code of 155, Putnam County has a population of 5,566 and area of 160 square miles (414 km2).
List of all cities in Putnam County, IL alphabetically
| City/Town | Postal Code | Area Code |
| Florid, IL | 61327 | 815/779 |
| Granville, IL | 61326 | 815/779 |
| Hennepin, IL | 61327 | 815/779 |
| Lake Thunderbird, IL | 61560 | 815/779 |
| Lake Wildwood, IL | 61336 | 815/779 |
| Magnolia, IL | 61336 | 815/779 |
| Mark, IL | 61340 | 815/779 |
| McNabb, IL | 61335 | 815/779 |
| Putnam, IL | 61560 | 815/779 |
| Standard, IL | 61363 | 815/779 |