Democratic presidential nominee Barack Obama, a longtime Chicago resident and the junior senator from Illinois, has planned what he hopes will be a celebration.
Anyone hoping to get close to Obama will need a ticket, and 70,000 are being distributed for the secure rally area in the park. But Mayor Richard Daley said he will not discourage anyone from coming downtown, The Chicago Tribune reported.
"You think I'm nuts? You think I'm not going to invite people down? This is a celebration," Daley said. "No way I'm going to tell people they should not come down and celebrate."
Police have warned that those with tickets will have to wait in long lines for security checks and searches, the Chicago Sun-Times reported. Those without can gather in the rest of Grant Park until it reaches capacity.
Police Superintendent Jody Weis said police will crack down on any bad behavior.
"We can't have foolishness," he said. "We can't have mischief."