Hardin county was made by taking the south end of Gallatin and the northeast part of Pope. It was created March 2, 1839, and was only 185 square miles in size.
The second smallest county in Illinois next to Putnam county. There are three towns in the county; Elizabethtown, with a 2010 population of 299; Rosiclare, 1160; and Cave-in-Rock, 318.
The first settler within the limits of the county was reported to be James McFarlan, Sr., who had a contract with the United States to furnish beef for the garrison at Fort Massac (Metropolis, Illinois). He settled at the present site of Elizabethtown in 1808, where the trail crossed from Nashville, Tennessee to the salt works at Equality.
Here McFarlan ran a ferry across the Ohio for twenty years. William McFarlan was also a settler as early as 1808. Benona Lee came in 1809. In 1808 Govenor William H. Harrison gave permission to Isaac White and Jonathan Taylor to operate a ferry at Elizabethtown. John King was the first cabinet maker. Mr. Ewell was the first teacher and Rev. Stilly, a Baptist minister, preached the first sermon in the county.
In 1839 lead was discovered on the farm of Mr. James Anderson, one mile south of the site of the present day town of Rosiclare. Nothing was done at that time toward developing the deposit. In 1842 a Mr. Pell, living one mile north of Rosiclare, discovered fluorspar and lead. Companies were organized and mines opened.
These mines were worked at intervals until 1851 when they were abandoned. Nothing more was done until recent years when the fluorspar mines were opened up. Since then there has been great activity in the fluorspar, zinc, and lead mining businesses. The mines are less than a mile out of Rosiclare. There were two railroads built, one steam and the other electric, leading to the river and used to move the raw products of the mines to the river where they are loaded on to barges for transportation to buyers. The mines were closed due to cheaper foreign competition in 1996.
Since 1965, the annual Hardin County Fluorspar Festival has been held in the fall in Rosiclare, Illinois to celebrate the influences brought to the area by the Fluorspar Mining Industry.