where was in the heat of the night filmed

Short answer:
The 1967 film In the Heat of the Night was set in the fictional town of Sparta, Mississippi but was primarily filmed in and around Sparta, Illinois, with additional scenes shot in other Illinois and Tennessee locations.

Main filming locations (1967 movie)

• Sparta, Illinois – Used to represent “Sparta, Mississippi,” including many of the small-town street scenes and landmarks.

• Freeburg, Illinois – Location for the opening railroad sequence.

• Dyersburg, Tennessee – Used for cotton fields and the Endicott plantation/house scenes.

• Chester, Illinois – Used for the bridge exterior scene and some surrounding shots.

• Belleville, Illinois – Additional town/location work for the film.

These real towns together created the atmosphere of a Deep South Mississippi town while allowing the production to shoot mainly in Illinois.

If you meant the TV series

The TV series In the Heat of the Night (1988–1995) used different locations:

• Season 1: Filmed mainly in Hammond, Louisiana.

• Seasons 2–7: Production moved to Covington, Georgia (and nearby towns like Conyers, Social Circle, and Milstead), often called “Hollywood of the South.”

Quick SEO-style extras

• Focus phrase: where was in the heat of the night filmed – For the film, think “Sparta, Illinois standing in for Sparta, Mississippi.”

• Meta-style description: In the Heat of the Night was set in Sparta, Mississippi but filmed mainly in Sparta, Illinois, with key scenes in Freeburg and Chester, Illinois, and Dyersburg, Tennessee.

TL;DR:
The movie was set in Sparta, Mississippi but filmed mostly in Sparta, Illinois , plus nearby Illinois towns and some Tennessee locations; the later TV series used Hammond, LA and then Covington, GA.

Information gathered from public forums or data available on the internet and portrayed here.