The film focuses on vignettes about the 4 young men: Curt, Steve, Terry, and John. Curt isn't sure he wants to go off to college, despite receiving a lodge scholarship, much to Steve's consternation. Steve, on the other hand, isn't sure about his relationship with steady girlfriend Laurie, Curt's sister. Curt spends the whole night riding around in other people's cars obsessing about a mysterious blonde in a White Thunderbird.
John splits his time between trying to pick up girls and defending his reputation as the fastest drag racer in town. Terry uses Steve's car to pick up a girl.
The movie gained some of its popularity through its music, see American Graffiti (soundtrack).
Warning: Wikipedia contains spoilers
Ironically, by the end of the night it's Curt who goes off to college, while Steve decides to stay in town and settle down with Laurie.
The film was nominated for several Academy Awards:
The unexpected success of this film helped to inspire ABC to give the green light for the television series Happy Days, which also starred Ron Howard and Cindy Williams.