GRAND CANYON NATIONAL PARK, Ariz. -

The site of a 1956 plane crash at the Grand Canyon that killed 128 people has been designated a national landmark.
   
The announcement was made Wednesday by Interior Secretary Sally Jewell and National Park Service Director Jonathan Jarvis.
   
Two planes collided on June 30, 1956, as they were flying 21,000 feet over the canyon near the confluence of the Colorado and Little Colorado rivers. All people aboard the two flights died.
   
The Federal Aviation Administration says the crash spurred discussion in Congress on managing airspace and controlling air traffic.
   
Federal officials say improvements that resulted from the crash included collision avoidance systems and flight data recorders.
   
Some 2,540 sites across the country are designated national landmarks. Jewell says they serve as reminders of triumph, tragedy, public service and artistic beauty.