I know I saw it during the summer of '71 because I was grateful for an air-conditioned theater. It ran as a double-bill with HoDS.
And MB recaptured the "nostalgia" of what it was like back then seeing movies. There were no mega-plexes back then, at least not in small (or probably even most medium-sized) communities, so it could take weeks for a movie to finally arrive, especially in a small town like mine. When it did, it played for a week (here, starting on Wednesday with nightly shows, along with matinees on Saturday and Sunday, and ending on Tuesday). That was it. We had only two movie theaters, each with one screen, while I was growing up (a third opened in the mid-seventies; actually re-opened after being closed and empty for more than a decade). You only got a chance to see four movies (remember, back then, a double-bill, starting with a "B" flic first, followed by the "A" one, along with a documentary, a cartoon and previews). Oh, wait, I forgot to say: we also had a drive-in that also showed double-bills, but it was open only seasonally. By the mid-seventies, double-bills had vanished, as did the documentaries and cartoons. If a movie was really popular, it would stay an extra week - "held over by popular demand," as it would say. The first movie in my small town that was "held over by popular demand" was The Poseidon Adventure. It stayed for three weeks. The theater that showed it tried to use its own "special effect." When the credits started, it closed the curtains over the screen and projected the images of the Poseidon rolling in the storm while fans blew the curtains around, trying to give a "wavy" effect. As the credits ended, the curtains opened.
Gerard