I'm currently a green card holder and have dual citizenship with the United Kingdom and Ireland. The country of birth on my green card is the United Kingdom. I would like to travel to Northern Ireland next month. Does it matter which passport I travel on? Can I travel back to the US with my green card and Irish passport if my UK passport is now expired? I sent my UK passport for renewal but it will be a couple of months at least before I receive the new one at the rate they are processing passport renewals.