…though apparently well-known in other parts of the world.  Based on an actual strike by Mexican-American workers against a zinc mining company, it is set in New Mexico, and uses actual mineworkers and their families in most of the main roles (including the male lead, Juan Chacon–his wife was played by a professional actress, however).   The movie is strongly pro-union, unsurprisingly, but much more  surprisingly, it has a strong pro-feminist twist, that wouldn't have been surprising in 1975, say, but is remarkable for 1954 (I won't spoil that part, you'll have to watch it).  The main writers and directors were blacklisted for refusing to cooperate with the fascist McCarthy Committee, but like other communist sympathizers at the time, they were, in ethical sensibility, well ahead of their time.  (At the end, the movie reveals which actors were "professionals" and which locals–there are several surprises.)