The road comedy is one of Hollywood’s simplest formulas. Get a pair of contrasting personalities, trap them on a plane, train or automobile with a strict deadline, and you’ve got comedy gold. “The Hangover” director Todd Phillips tries his hand at the genre with Zach Galifianakis and Robert Downey Jr. in “Due Date.” We compiled a list of some of the finest road comedies ever made.

1 “Planes, Trains and Automobiles” (1987): Contrary to popular belief, John Hughes’ greatest achievement was not one of his teen movies, but this hysterical and surprisingly emotionally resonant road comedy with Steve Martin and John Candy. The late, great Candy was never better than in this near-perfect comedy.

2 “It Happened One Night” (1934): Frank Capra’s comedy classic with Clark Gable and Claudette Colbert is one of only three movies to sweep the five main Oscar categories (actor, actress, director, screenplay and best picture). Though dated, this is still a joyful journey with a spoiled heiress and a wisecracking reporter.

3 “Lost In America” (1985): It’s sad that so few people appreciate the genius of Albert Brooks these days. Though mostly forgotten, Brooks wrote, directed and starred in this gem about a pair of yuppies who quit their jobs for the open road. It’s easily one of the finest and most emblematic comedies of the ’80s.

4 The Hope/Crosby “Road To” Pictures (1940-1962): No discussion of road comedies would be complete without mentioning Bob Hope and Bing Crosby’s still-hilarious series of “Road To” movies (often parodied on “Family Guy”). “Road To Rio” is arguably the best, but they’re all pretty good.

5 “National Lampoon’s Vacation” (1983): The ’80s comedy dream team of screenwriter John Hughes, director Harold Ramis and star Chevy Chase may have spawned a successful franchise with “Vacation,” but the original trip to Walley World remains the darkest and the best. Yes, even better than “Christmas Vacation.”