ER (2009)
By the time NBC got around to airing the series finale of ER, plenty of viewers had already tuned out. The show, tracking the fictional denizens of Chicago's County General hospital, reached nearly 50 million viewers at its peak. By last year, however, regular viewership was down to around 8 million. Nostalgia pulled people back for the conclusion of America's longest-running primetime medical drama and 16.4 million people watched the 331st episode on April 2, 2009. The show ended as it started, with ambulances blaring and the emergencies continuing. "I really wanted to say to the audience, 'This place is still here,'" executive producer John Wells told Entertainment Weekly, "and if you took the wrong off-ramp in Chicago, you'd end up in front of the hospital where these people have always worked.'"