Litchfield is a city in Montgomery County, Illinois, United States. The population was 6,605 at the 2020 census. It is located in South Central Illinois, south of Springfield, the state capital. Earlier, Hardinsburg, about 2 miles to the southwest, had been founded about 1850. Both towns were created in anticipation of the Terre Haute & Alton Railroad. Hardinsburg grew to about 50 people by 1854; but when it became clear that the railroad was going through Huntsville instead of Hardinsburg, many of the buildings in Hardinsburg were pulled across the prairie on runners to Huntsville beginning in January 1854, and most of the residents moved to the new site as well, becoming Litchfield's first residents. The railroad reached Huntsville in the autumn of 1864, and within two more years Hardinsburg had substantially disappeared.