The Library of Congress National Recording Registry has added 25 songs to it’s list. Anyone can nominate recordings (songs, interviews, etc) for inclusion. Criteria include: Recordings selected for the National Recording Registry are those that are culturally, historically or aesthetically important, and/or inform or reflect life in the United States.
Apparently the artists need not be American. What would you include if you nominated a tune? The current list will be in the comments for reference.