What is the most efficient method to convert EUR from Ireland into USD in the United States?

SWIFT Wire Transfer would be the safest and most convenient bet. The rates offered by banks for Wire transfer from Euros to USD would be TT (Telegraphic Transfer) wire rates and are as good as it gets. The cost of funds transfer would most likely be US$ 50 (at best) for the Wire transfer itself and about 1.5% on the exchange rate.