People arrived Saturday morning to find giant concrete barriers blocking the entrance to the park where the car show was to be held.
The head of the park district says the closure was ordered by Dolton Mayor Tiffany Henyard, because she had a competing outdoor event a few blocks away.
Problem is, he says, is that Henyard has no legal authority over park district property, which is run by a separate government agency.
"We're trying to understand why would she shut down an event and not allow the public into their own park," said Cleo Jones, Dolton Park District President. "I would like to see those boulders removed immediately. I'd like to have a meeting with the mayor. And have a meeting with the village trustees and let them know this cannot happen again."
The mayor did not return FOX 32 Chicago's email asking for comment.
The car show was moved to another park in a nearby suburb.