FreeImages.com/Ernesto Ferreyra1990: The television drama "Law & Order" premieres. The show would last 20 seasons and spawn four spin-offs before ending in May 2010, making it the longest-running crime drama on American primetime television. After "The Simpsons," both "Law & Order" and "Gunsmoke" are tied for the second longest-running scripted primetime series with ongoing characters.