The 1950s was the last major decade for movie musicals that were made specifically for films. By the middle of the decade, most of the movie musicals were adaptations of Broadway plays, especially the plays of Rodgers and Hammerstein.
The beginning of the decade saw a few musicals that were more typical of the previous decades. These musicals, such as "An American in Paris" and "Singin' in the Rain," had original stories with weak plots (usually "boy meets girl, boy falls in love with girl, boy chases girl, boy gets girl"), and music that had been used in earlier movies or Broadway musicals. The emphasis in these movies was often on the dancing, especially when Gene Kelly or Fred Astaire were the stars.
The latter part of the decade saw a shift to movie musicals that were based on successful Broadway musicals, such as "South Pacific" or "Oklahoma." Although some of these films had strong story lines, they were still heavy on dancing, often with big production numbers.
Two movie musicals of the 1950s won Academy Awards as Best Picture - one at the beginning of the decade ("An American in Paris" in 1951) and one at the end of the decade ("Gigi" in 1958). Both movies had screenplays by Alan Jay Lerner (he won for best screenplay for both films) and both were directed by Vincente Minnelli (he won as best director for "Gigi"). Both "An American in Paris" and "Gigi" were produced by M-G-M studios. The major differences between the two movies were that "Gigi" had a stronger storyline and completely new music, created just for the movie, but there was virtually no dancing in the film. In contrast, "An American in Paris" was acclaimed for its dancing, but its storyline was weak and it had no new songs.