The Great Irish Famine (1845-51) reduced the population of Ireland by a quarter, and was the start of mass emigration from the Emerald Isle. With movement out of Ireland on such a scale, passenger lists and travel records have become very important resources for anyone tracing their Irish roots.

From travel and emigration records you can usually find out where your Irish ancestors went, the ship they travelled on (these were the days well before airplanes!) and who they travelled with.

Source & Full Story