And it's because of the size of the event that organizers decided to try out a new route this year by extending the parade an additional five blocks.
At the Pride Festival on Addison and Halstead Saturday, people were already celebrating.
About 750 thousand people are expected to line the streets in Uptown and East Lakeview for Sunday's Gay Pride Parade.
Organizers lengthened the route in an attempt to thin the crowds.
"Last year it was really bad, packed, too crowded," said Val Tompkins. "We couldn't see it, there were 10 rows of people."
Tompkins and and Trisha George drove from Coldwater, Mich., to see the parade. They say last year, some areas were dangerous.
"There were kids getting pushed," George said.
In addition to the route being extended by five blocks, there will be more designated spots for people to cross the parade route.
There's also a new starting point. The floats and flags will now start moving on Montrose and Broadway in Uptown.
The new parade route then proceeds south on Broadway to Halsted, then to Belmont. It will travel east on Belmont, back to Broadway, then to Diversey.
It's expected to last about two hours and 15 minutes
"We are asking people to come to the beginning of the route," said parade coordinator Richard Pfeiffer. "Halsted will be busy with the bars. Come to the first few blocks."
Pfeiffer is also alerting parade watchers to watch their alcohol consumption. This year, police will be cracking down
"Technically, there is an ordinance about open container," Pfeiffer said.
Emergency officials are warning people that it will be warm out so if you're going to Pride, wear loose fitted clothing, drink plenty of water and seek shaded areas.