Article: Eisenhower retired to the place where he and Mamie had spent much of their post-war time, a working farm adjacent to the battlefield at Gettysburg, Pennsylvania, only 70 miles from his ancestral home in Elizabethville, Dauphin County, Pennsylvania. In 1967 the Eisenhowers donated the farm to the National Park Service. In retirement, the former president did not completely retreat from political life; he spoke at the 1964 Republican National Convention and appeared with Barry Goldwater in a Republican campaign commercial from Gettysburg. However, his endorsement came somewhat reluctantly because Goldwater had attacked the former president as "a dime-store New Dealer".

Now answer this question: Who did Eisenhower donate his farm to in 1967?
National Park Service