Flying DUB to SLB -- one option is AA arrving 12:30pm chicago O'hare connect to DL 4pm. I'm assuming 3 hours is enough time to make it through customs and change terminals. I've had tons of bad weather and/or delayed AA flights connecting in O'hare so wondering what happens if I miss the DL flight. Would DL care if AA is delayed? Does immigration in Chicago get really backed up?