Why "go to the movies" and not "go to a movie"

Why do we use Do you ever go to the movies? and not Do you ever go to a movie? Is the latter also correct?

Solution 1:

Per the Macmillan Dictionary, the movies refers specifically to "movies as a form of entertainment," or, secondarily, "the industry involved in making movies."

(In the British version of Macmillan, the movies refers to "the cinema or the film industry.")

Solution 2:

"Movies" is short for "moving pictures". Since "moving pictures" was plural, its short form was naturally also plural.

In the early days of its use, moving pictures was commonly used in plural form to refer to a single film; for example, the OED has:

1897 Sketch 13 Oct. One guinea and half-a-guinea are being asked for stalls to see the moving pictures of the Corbett–Fitzsimmons fight at the Empress Theatre.