21 Jump Street S4 - 21 Jump Street was an hour-long action/drama series that ran officially from 1987 until 1991. In total, five seasons were made, and the show was canceled in 1991 due to low ratings. Most of the original cast (Hanson, Ioki, and Penhall) had already left by then, leaving behind only Hoffs and Fuller, alongside a few new faces. The show is most famous for rocketing actor Johnny Depp to fame. 21 Jump Street was about a group of under-age looking cops who went undercover on high schools to catch young criminals before they become older, more dangerous criminals. In later seasons, the team went less and less undercover on high schools, and the plots focused more on the cops' personal lives.