Immigration from Italy to Ireland to US
 

I'll be taking a trip to Europe in August (I'm from the US). My return trip to the US is Rome - Dublin - New York, but its just a quick layover in Dublin. My tickets for the flights (Rome/Dublin and Dublin/NY) where booked separately so they are not combined, however, they are on the same airline. I've heard about the different travel zones in the EU and am wondering if anyone has information regarding immigration/customs/security that I'll need to go through in Dublin. I have just over a two-hour layover in Dublin and am worried that is not enough time if I have to go through immigration, customs, and security. Any advise would be much appreciated. Thanks in advance!

What airline are you flying? Many airlines will check you luggage all the way through from Rome to the US. This will make your transfer faster than if you need to claim luggage and recheck it.

No immigration from Rome to London, and no customs, There may be another security check. Someone who has been through Dublin recently can tell you that.

I would talk to a human at the airline.

You will go through security and passport check in Rome (as Ireland isn't in Schengen), where you should get Schengen exit stamp. If you are staying airside, there should be no passport control in Dublin, and no customs and rechecking your luggage if it's through-checked at Rome (ask). There will be strict security procedure at Dublin as you are travelling to US (there will be one at the gate), and you also go through US immigration as Dublin has pre-clearance.

Thank you all for your help! Really appreciate it. :)