IRISH people whose families left this country and headed for the US will be able to trace their relatives as the US government releases the 1940 census to the public.
Access to the records will be free and open to anyone on the internet from April 2 -- but they will not be immediately name-searchable.
For genealogists and family historians, the 1940 census release is the most important disclosure of ancestral secrets in a decade and could shake the branches of many family trees.
Researchers might be able to follow the movement of refugees from war-torn Europe in the latter half of the 1930s.
Henry Gates, a Harvard University professor, said the "goldmine" of 1940 records would add important layers of detail to an existing collection of opened census records dating to 1790.
"It's such a rare gift," he said of the public's access to census records, "especially for people who believe that establishing their family trees is important for understanding their relationship to American democracy, the history of our country, and to a larger sense of themselves".
But some experts say enthusiasm for the release could be dampened by the lack of a name index, especially for novices.
"It may very well frustrate the newcomers," said Thomas Macentee, an industry analyst.