The Union Pacific/Northwest Line(METRA) in Harvard Il(just south of the WI border) will take you to all the way into town(bout a 1.75 hr ride, depending on stops), but i would recommend getting off at the Irving Park stop(15 mins shorter) and taking the Irving Park East bus to Clark, then just walk 4 blocks south. Otherwise you can drive down to the Blue Line(CTA) at O'Hare, go downtown and transfer to the redline(Get off at addison), but that's around a 35 min ride or so. Personally, if you are looking for an easy way, i'd take the blue line to the redline and up to addison. It's easy, and both Blue and Red lines run 24/hrs(no other lines run past 2am on weekdays, and the NW line shuts down at 12:30am), so if you feel like hitting up the bar scene after the game, you don't have to worry about missing the last train to harvard. Also, minimal traffic(compared to driving all the way in to downtown) once you get out towards O'hare. Honestly? Parking there is overpriced. I'd park at a CTA train stop(i'd stop at the yellow line if you are coming from Milwaukee, it's a nice neighborhood and the farthest north stop), and take the train in. As long as you paid for the parking spot there($3 all day, IIRC), you are good to go.