Librarian Georgette Bordine at Camelback High School in Phoenix said the books were checked out in 1959.
Bordine said that she received a package containing the two library books with a letter, along with a 1,000-dollar money order to cover up the fines.
"It was just so overwhelming," the New York Daily News quoted Bordine as saying.
Bordine said that letter explained that the family of the former student, who wanted to remain anonymous, moved to another state and the books were mistakenly packed, Bordine said.
The letter said the money order was to cover fines of 2 cents per day for each book. That would total about 745 dollars.
The letter says the extra money was added in case the rates had changed.
Bordine says she'll use the money to buy new books for the library. (ANI)