I am flying to Chicago and meeting up with a friend who is flying in from a different city. We will then travel on together to Winnipeg. We are both on United flights and have a 3 hour layover in Chicago. What would be a good place for us to meet up with each other?

I'm assuming you just need the general area and can do an exact meet up by phone.. Near the food court between concourses H & K is an obvioius choice. Chances are good that 1 if not all 3 of your flights are into or out of H or K...

I thought all the United flights were out of Terminal 1 (except some of the RJs use Terminal 2), and Air Canada uses Terminal 2,. H and K are in Terminal 3 which is the OneWorld terminal and where United and AC don't operate?

LOL. You're right. I mixed up AA H/K gates with UA. I use them both through O'Hare....

Trying to respond to the OP: If they are both arriving on 6 seat across jets (so Terminal 1), then they could meet at the connector for Terminal 2, the skywalk or whatever term you use, near the entry to the United Lounge. I don't know the airport that well, like Schiphol O'Hare is huge, almost everything in one sprawling building.