Parking restrictions along the 2200 and 2300 blocks of S. Indiana Ave. went into effect early Sunday morning.
Cars left on parked on Indiana between Cermak and 24th St. were towed.
Indiana is the first north-south street west of McCormick Place.
More parking restrictions and road closures will be added later on in the week.
Meanwhile, groups of people opposed to NATO hosted day two of their People's Summit Sunday.
Organizers say the event, which was held at the headquarters of Occupy Chicago is a workshop for people to voice their ideas for the future.
"This is a chance to really involve people and engage the public in planning a better world- it's the absolute opposite of NATO," said Natalie Wahlberg.