Wa it a general release film, or sold as an art house production?. I was a touch young at the time, so I dont have any clear memory except being astounded when I saw it on TV
General release. I think it was '71 or '72 - I was working for WB(the distributor) at the time. It was American Zoetrope's first feature, and while I loved it, of course all the money boys in the room cared about came to the surface a season or two later. We (WB) got THX1138 and someone else (I think UA or Paramount?) got American Graffiti!
I saw THX1138 in a screening room. I think it did one week in its first run (I was in Montreal) in a small-ish outlet. I liked it sufficiently that I went to the theatrical release, too. Good movies should be seen on the big screen.
Far too heady a film for the sci-fi crowd at the time. They all wanted spectacular effects like 2001: ASO. I figured they'd re-release it, because it had had literally no audience, after the success of American Graffiti with a build-up as The American Graffiti Guy's First Feature! They didn't, but tried after Star Wars. It flopped again.
I was very taken with it, originally. I'd have to see it again and think I will get a copy. At the time, I was totally taken by both Duvall and Pleasance, but found that the plot/storyline was quite brilliant.
I'd also love to get my hands on his original version - the one he made in film school. A friend of mine knew Martin Scorsese rather well and he said it was one of the tightest edited pieces he'd ever seen. (And Marty loves him some editing, he does!)