40 Minutes for connecting flight In chicago Ohare?

[treeface]

As PP's said, O'Hare is huge, but it is manageable. I often have to connect through there as it is one of the few airports our regional airport has connections through. That said, I have had 45 minute layovers and not had a problem making it (or having my luggage make it). Whatever happens, you'll still make it to your destination.

 

[TOTALLYGOOFY]

Frequent Fly out of O'Hare
O'Hare has four terminals - One, Two, Three, and Five (Four is another story.)
United is at Terminal 1 which has two sections - Concourse B and C connected with a futuristic neon-lit underground walk-way.

For walking, the farthest gates is Gate 1 to Gate 32 of Concourse C and B Concourse is B 1 to B 17 / B 21. Funny, both concourses are the same lengths though. Yes, you can walk to any one of these gates given how fast you can exit the plane. My experiences, connecting gates are close together. If you have to go between the two concourses, walk very fast, no loitering for post card.

Here's maps of O'Hare and Untied Terminal One. Print and take with.
Google : chicago o'hare ord airport terminal map

Since gate assignment change, at Logan, ask the ticket agent, what will be your arrival gate and departure gates at O'Hare. Also, your in-flight magazine will have a map of the airport. Your good to go.
Enjoy the view of Lake Michigan and the Loop if your seating on the port/left side of the plane.