Hancock County is a county located in the U.S. state of Illinois. According to the 2010 census, it has a population of 19,104, which is a decrease of 5.1% from 20,121 in 2000. Its county seat is Carthage. Hamilton is the largest city in Hancock County, with Carthage being the second largest. The county is made up of rural towns with many farmers.
Hancock County was part of the "Military Tract" set aside by Congress to reward veterans of the War of 1812. Actual settlement of the interior of the County was delayed by concerns about hostile American Indians. After their defeat in the Blackhawk War in 1832, settlement proceeded quickly.
For a brief period in the 1840s Hancock had one of Illinois' most populous cities: Nauvoo, which was then headquarters for the Church of Jesus Christ of Latter Day Saints. The LDS leader Joseph Smith, Jr. was killed in the county seat of Carthage in 1844. Most Mormons left Hancock county in the 1840s. Today followers of the LDS movement come, in increasing numbers, to important LDS sites in Hancock county, partly for vacation and partly for religious pilgrimage.
The original courthouse was located at Montebello. Montebello no longer exists but was between Nauvoo and Hamilton. In 1833 the state commissioned the formation of the county seat at Carthage IL which was centrally located but not well developed at the time. A log cabin was built to serve as the courthouse and continued to serve that purpose until 1839 when the second Carthage Courthouse was built. The original log cabin continued to serve as a school and other purposes until 1945 when it was removed.
The second courthouse cost $3,700 dollars to build and served from 1839 until 1906. It served as a location for both Stephan A. Douglas (October 11, 1858) and Abraham Lincoln (October 22, 1858) to speak to residents of the area as they were running against each other for the US Senate. In 1906 it was removed to make room for the current courthouse.
The current courthouse was dedicated October 21, 1908.