Chicago is also where the future Obama presidential center will be built, near the former leader's home in the southern part of the city.
Obama took a private elevator with his security to the room, where he shook almost every hand.
Cook County Chief Judge Timothy Evans said the former commander in chief "promised to do his duty" and was assigned to a panel that was not called to serve on a jury. But he was not picked to serve as a juror.
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Nat King, 50, called congestion on one of the area's main thoroughfares "the one issue that I know has to be addressed". She and her supporters knocked on doors more than 75,000 times in the district, which contains 52,471 registered voters.
On Wednesday, Obama did get the prospective juror experience of sitting through a decades-old, 20-minute video in which Lester Holt- now the anchor of NBC Nightly News but back then on local news -explained the ins-and-outs of jury duty. The visit was "not disruptive at all", he added, despite heightened security, massive lines to enter the building, and plenty of onlookers.
For his day of public service, he will presumably receive the standard payment for every Cook County juror, which is $17.20.
"There is a civilian responsibility for justice to take place and that's what jury service is all about". When he arrived there was a feeding frenzy as crowds of people inside the courthouse took photos and videos of the former president. Obama asked the person with a smile.
While the Obamas now live in Washington, the former president and first lady Michelle Obama maintain a home in Chicago, the city where he got his political start.