He cast his vote on a 100% unverifiable touch-screen e-voting system made by Sequoia Voting Systems (which is now owned by a Canadian firm named Dominion Voting.) It is scientifically impossible to ever know if his vote was recorded accurately, as per his itent, or not on that type of voting system.
"I can't tell you who I voted for," the President joked, as noted by our colleague Mark Crispin Miller in a short blog item today wryly headlined "Obama votes for Romney". The President's joke may not have been nearly as funny as he had intended it.
We confirmed with the Chicago Board of Elections that Early Voters in the Windy City must do so on the oft-failed, incredibly-vulnerable, and easily-hacked (see below for details) Sequoia AVC Edge touch-screen voting system which is still used according to VerifiedVoting.org's database for Early, Disabled-Accessible or Standard polling place voting in some 234 jurisdictions across all or part of some 13 states, including Arizona, California, Colorado, Florida, Illinois, Louisiana, Missouri, New Jersey, Nevada, Pennsylvania, Virginia, Washington and Wisconsin.