Gillespie is a city in Macoupin County, Illinois, United States and part of the Metro East region of the St. Louis metropolitan area. The population was 3,319 at the 2010 census.
The first group of settlers arrived to what is now present-day Gillespie in the late 1820s from Kentucky, Ohio, and Indiana. The township thrived in the 1830s, increasing in population and businesses. In 1835 the first schoolhouse was built. Gillespie was officially incorporated as a town in the spring of 1853. By 1904, the population rose to 3,100 and there were a number of businesses, churches, and schools. On January 29, 1905, a giant fire swept through the entirety of the business district and destroyed most businesses and some homes.
For years, Gillespie's main source of employment was the multiple mines scattered throughout the township operated by the Chicago & Northwestern Railroad Company. It is said that Gillespie boasted three of the largest coal mines in the world.
Gillespie is named for Judge Joseph Gillespie, who was active in Illinois state politics.
Gillespie is home to Gillespie C.U.S.D. #7, which operates Gillespie High School, Gillespie Middle School, and Ben-Gil Elementary School.