The DC-9 entered service in 1966, I believe it was, as a direct competitor for the Boeing 737.
Northwest Airlines and Midwest Express both still operate DC9-10s. They can be seen regularly at Milwaukee General Mitchell Airport and Minneapolis/St. Paul. They are flown on short routes. They are so small, they look almost like the new regional jets which are becoming so common on feeder lines.
One of the most notable crashes involved a Hughes Airwest DC-9 and a McDonnell Douglas F4 Phantom, which collided over the Los Angeles Basin. The F4 pilot ejected safely, but the DC-9 fell out of the sky into Fish Canyon, with the loss of all aboard. Hughes' colour scheme was then changed from all-white to bright yellow for visibility, the all-white fuselage having contributed to the collision as it blended in with the clouds. Another more recent and notable crash was another mid-air collision, between a Cessna and an Aeromexico DC-9, over Los Angeles. The DC-9 lost its entire horizontol stabliser and fell inverted into a residential area, again with the loss of all aboard.