"They approached Peter Schivarelli, our manager, and asked if we'd like to come and play a few songs at a free concert to introduce Rahm to the Chicago public, and we said yes!" said Chicago band member Lee Loughnane.
While the show was a treat for their fans, the band says it was also exciting for them -- a first in a career that spans four decades.
"It's a new beginning for the city of Chicago and we have felt like we've been carrying the name of this city all over the world for all these years with a lot of pride and to be here in town and deliver that in person is really a treat," said Chicago band member Jimmy Pankow.
"This is a first, we're at a first and we're gonna be part of it and we'll be able to say to our kids and to each other later today and go, 'Did we really do that?' We just feel like lucky guys to be a part of history," said Chicago band member Walter Parazaider.
When asked about their non-stop schedule, Chicago band member Robert Lamm replied: "Sure I get tired like everyone else, but I'm kind of down at the end of a tour -- I can't wait 'til the next leg begins -- I'm crazy, I think!"
Before Saturday's concert, Chicago warmed up and waited in the green room, which is underground at the Petrillo Band Shell. Once the band took the stage, fans were elated despite the rainy weather.
"We make people happy. We're in the happiness business and thank God we are! "said Chicago band member Walter Parazaider.