If you're missing this once in a lifetime chance to see Peter Watkins' amazing body of work, take comfort in the fact that you are not alone. From Peter Watkins' website:

‘Punishment Park’ was released in the Murray Hill Cinema in an out-of-the-way part of Manhattan, New York City, and already it was clear that the US distributor was not going to properly handle the film. It remains unclear whether the cinema owner (or the distributor) was affected by the hostile critics, or whether the Federal authorities issued threats. In any case, ‘Punishment Park’ was withdrawn from the cinema after only four days. Since then, ‘Punishment Park’ has rarely been shown in the US, and never on TV. A representative of a main Hollywood studio which could have released ‘Punishment Park’ was quoted as saying something to the effect that, “We could never show this film, we would have the Sheriff’s office [or perhaps ‘the Federal authorities’ - PW] on our necks in five minutes.” Participants at a seminar for TV producers from 24 Public Broadcasting System (PBS) stations across the US all swore that they could never, and would never show a film like this on American TV. And so they haven’t.

(note: you can still catch Punishment Park Friday June 11 at 7pm at Anthology Film Archives)