Gillespie is a city in Macoupin County, Illinois, United States. The population was 3,412 at the 2000 census.
Gillespie is located at 39°7′34″N 89°48′59″W / 39.12611°N 89.81639°W / 39.12611; -89.81639 (39.126023, -89.816403).
According to the United States Census Bureau, the city has a total area of 1.5 square miles (3.8 km²), all of it land. Gillespie has large lake, Lake Gillespie, just outside the city limits. Many people from surrounding towns enjoy fishing, boating, water-skiing and sunbathing at Gillespie Lake.