• Uber threw a party for its drivers in Chicago on Monday that drew many more people than the ride-hailing company likely anticipated.
  • The event at Chicago’s Museum of Science and Industry was billed as a driver-appreciation party, where Uber drivers were each allowed to bring three guests.
  • But so many people showed up that it caused a traffic gridlock in a section of Hyde Park, according to a report from The Chicago Tribune.
  • “That many people going to one place is just dangerous,” local resident John Morrison told The Chicago Tribune, recalling that he saw vehicles, including a bus, driving on the wrong side of the road just to bypass the traffic.
  • Visit Business Insider’s homepage for more stories.

An Uber driver-appreciation party on Monday evening drew so many people to Chicago’s Museum of Science and Industry, it caused traffic gridlock in a portion of Hyde Park.

A report from The Chicago Tribune described an army of people and vehicles heading toward the venue around 6:30 p.m., apparently prompted in part by Uber’s move to allow drivers to each bring three guests to the party.

Uber spokesman Josh Gold said in a statement to Business Insider on Tuesday that the company is “thankful for the thousands of partner drivers and their families who attended” the party.

“However, over a thousand more than RSVP’d came and we had to close admission to the event for everyone’s safety when the rented portion of the venue reached capacity,” Gold said.

Read more: Uber's first passenger drone is a helicopter-plane hybrid that can carry passengers across cities at 150 mph

John Morrison, a Chicago resident cited by the Tribune, said "that many people going to one place is dangerous," recalling that he saw vehicles, including a bus, driving on the wrong side of the road just to avoid traffic.

Social media video and images show the venue itself was also crowded.

http://instagr.am/p/ByjY3VknBx0

One Instagram user posted video from inside the event with a caption that read:

"We arrived 30 minutes after the posted start time and found almost every exhibit closed, every #uber driver in Chicago in attendance, and zero food or drinks (after waiting in line at the food table for nearly an hour). It was a bummer of an evening, to say the least."

Uber has a fraught history with its drivers, who are officially recognized as independent contractors. Some drivers have previously sued the company for recognition as employees - a designation that would allow them to unionize. The National Labor Relations Board last month issued a memo denying that request and dashing hopes of recognition at the federal level.