Navy Pier announced just before 2 p.m. Saturday that all on-site parking garages were filled to capacity.
The announcement came more than five hours before the venue was set to hold its second holiday fireworks show, which was scheduled to light up the sky at 10:15 p.m.
The pier's parking garages filled to capacity just before 2:30 p.m. Friday.
Partner parking garages-- including the Grand Plaza Self Park at 540 N. State St., the Ogden Plaza Self Park at 300 E. North Water St., and the Millennium Lakeside Garage at 5 S. Columbus Ave.--are available at a discount rate of $15 for 12 hours, but still expected to be crowded.
Visitors were being encouraged to take public transportation as well. The pier closes at midnight but trolleys will offer transportation to parking garages up to 1 a.m.
Tens of thousands of visitors gathered at Navy Pier Friday, many dressed in patriotic attire, hoping to make it into the venue for the annual fireworks show.
Gates closed around 7 p.m. as the venue reached capacity. No additional visitors were being allowed inside, officials said.
The pier was expecting roughly 125,000 people to watch the holiday fireworks, more than double the average summer weekend crowds, and issued a special crowd advisory for those planning to visit Friday or Saturday.
"We anticipate that at some times on both days, to ensure the safety and comfort of all guests, Navy Pier will reach capacity and the gates will close," their website read.
Chicago Police had to turn away people last year after Navy Pier reached capacity, and pier personnel said it wasn't a matter of if it reached capacity again this year, but when.
"Last year, first the garages filled up and then at a certain point we reached capacity," said spokesman Nick Shields. "We expect the same thing to happen this year."