I thought it was Robert Kennedy’s 50 mile hike in February 1963 that kicked off it’s preservation, but actually it’s a quarter century older then that with the intention to become a park.

It was President Franklin Roosevelt’s administration that purchased the it from the B&O Railroad in 1938 with the intention of turning it into a park. The World War got in the way, and it was stuck on a back burner to becoming an official National Park, until on Dwight Eisenhower’s last day in the White House in 1961 he designated it National Historic Landmark.

In February 1963, Attorney General Robert Kennedy and several other Kennedy staffers on the President John F. Kennedy’s challenge did a 50 mile hike on trail. But it was still just a National Historic Landmark until 1971 upon the lobbying of then former Supreme Court Justice William O. Douglas it was upgraded to a National Park.

Now, the entire Canal is well signed and a excellent gravel bike path from Washington DC to Cumberland MD.

A fairly extensive history on the creation of the C&O Canal National Park.