Cuba is sending the US copies of more than 20,000 papers relating to the Nobel Prize winning American writer Ernest Hemingway.
The move is part of a deal on restoring Hemingway's legacy that, correspondents say, has united the usually feuding governments of Havana and Washington.
The papers sent to the US Library of Congress include copies of Hemingway's letters and some of his famous novels.
Hemingway spent much of his time living in Cuba between 1939 and 1960.
Marta Arjona, the head of Cuba's National Heritage Council, said the documents being sent to the US amounted to an "invaluable" gift relating to that period.
She told Cuba's Communist Party newspaper Granma that the move was part of an agreement, reached in 2002, to restore and digitalise some 11,000 documents relating to Hemingway.
The documents sent include copies of letters in which Hemingway outlines his stance on World War Two and the Spanish Civil War.
Copies of his novels, For Whom the Bell Tolls and The Old Man and the Sea - inspired by his time in Cuba - have also been sent to the US.
The originals are expected to remain at a museum at the writer's former house in Havana, Cuba.
Under the agreement, US experts have travelled to Cuba to help restore the museum, Ms Arjona said.
But she pointed out that Cuba had met all the costs of the restauration.
The museum, the Museo Ernest Hemingway, is in the house where the novelist lived while he was in Havana.
Established in 1962, it houses the writer's furniture and personal possessions, as well as works of art and books.
