United Airlines is to start serving Shannon in Ireland from its Chicago hub next summer.
The new seasonal route will run five times a week between June 16 and August 23, 2013.
The carrier is also raising frequency on its Heathrow-Houston route by adding a third daily Boeing 767 flight from March 30.
Shannon will be served by a 169-seat Boeing 757 in a three-class configuration. Outbound passengers will be able to clear US customs and immigration before departure at the Irish airport.
President and chief executive Jeff Smisek said: “These new flights offer travellers more choice and convenience while our continuing investment in new aircraft, onboard products and services and technology results in a better travel experience for customers.”