American Honey Sasha Lane, Shia LaBeouf, Riley Keough. Directed by Andrea Arnold. Rated R. Opens Friday at Regal Colonnade and Village Square.

The credits for American Honey feature only a list of names, with no breakdown of individual roles for cast or crew. That’s a reflection of the way British writer-director Andrea Arnold crafted the movie, recruiting mostly non-professional actors, improvising many of the scenes and shooting in chronological order while the entire cast and crew traveled across the U.S. The result is meandering and shapeless, but it has a bracing authenticity that’s tough to dismiss completely.

Still, with a running time of nearly three hours, the movie is often a chore to watch, especially as Arnold focuses on the volatile relationship between Star (newcomer Sasha Lane) and Jake (Shia LaBeouf at his grodiest), two members of a “mag crew,” a group of young people selling questionable magazine subscriptions door to door. Star fixates on Jake and the mag crew as a way to escape her dead-end town and abusive home life, but Jake isn’t much better, and their tedious cycle of fighting and screwing drags on interminably.

Outside of that central relationship, though, Arnold captures a striking look at American life on the margins, with some beautiful cinematography and a casual, lived-in vibe among the supporting characters. A documentary about mag crews, a real phenomenon, could have encapsulated Arnold’s vision of American poverty more concisely.