I noticed today that the departure time for our return flight from Shannon for our ABD next summer had changed and was now leaving 2 hours later than originally scheduled, which left us with a 48 minute layover at JFK. I called Delta today and changed our flight so we now have a 1 hr 54 min layover hopefully sufficient time to clear immigration and customs without me freaking out. I then began to wonder how long the typical wait might be at JFK and, in the course of a quick Google search, I found the link below. It provides historical data on how long it takes for travelers to clear passport control at major airports in the US. Its broken down by terminal and shows hourly data, so you can check the time of day when your flight is scheduled to arrive. Of course, its historical data, but potentially useful if you just need an idea of how long your wait may be, so I thought I would share.
http://awt.cbp.gov/
http://awt.cbp.gov/