O’Hare is large, and they were to be a good airport to drop off a letter that you’ve written during a layover. But I’ve heard recently via Instagram that the boxes may have all disappeared.
No drop boxes are available as of late 2021. All drop boxes listed below were post-security and removed. I will need more information if there is a pre-security drop box.
Previous Official Information
Post Security Drop Boxes
In their FAQ:
There is no post office at O’Hare but there are mail collection boxes scattered throughout the terminals:
Terminal 1, Concourse B, Gate B9
Terminal 1, Concourse C, Gate C18
Terminal 3, Concourse H, Gate H1, Across from the Starbucks
Terminal 3, Concourse L, Gate L2A, Across from Publican Tavern
Terminal 5, Concourse M, Gate M8
Last updated 21 April 2021