Passenger manifests dating from 1890 to 1960 are to be released by the National Archives and placed online.
The information is expected to help people looking to track down British relatives who emigrated abroad during that time, as well as showing the movements of European migrants.
However, the first batch of data to go online only covers 1890 to 1899, with further information being added over the coming months.
It is estimated that almost 125,000 Britons emigrated to America every year between 1890 and 1914.
During the same period, 50,000 migrants started a new life in Canada and 25,000 people moved to Australia.
Dan Jones, head of business development at the National Archives, said that he hoped the digitisation of the records would open up a hugely valuable resource for genealogists and social historians all over the world.
The information includes trips to every continent, including sailings to Asia, West Africa and the Caribbean.
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