Genre
Musical; Romance; Drama
Musical
What makes An American in Paris a musical? Didn't you catch all of that delightful singing and dancing? A lot of it was even done by Americans in Paris.
An American in Paris is an integrated musical. That's a fancy way of saying that all of the musical numbers pop up organically. Nobody suddenly launches into a song about their favorite pair of shoes over dinner. The songs' subjects are part of the story, and characters kick up their heels because the narrative's given them good reason to.
Take "Tra-La-La (This Time It's Really Love)," for example. Jerry starts singing and dancing all over Adam's apartment because he's just locked down a date with Lise and, well, he thinks that this time it's really love (tra-la-la). Similarly, when Henri belts out "I'll Build a Stairway to Paradise," it's part of his Paris stage show, and we're treated to front-row seats. Even the dizzying dream sequence fits naturally into the film's narrative because it's all taking place in Jerry's lovesick noggin.
Romance
An American in Paris isn't all singing, dancing, and dream sequences. It's also the story of Jerry falling in love with Lise, and Henri already being love with Lise, and Lise not being sure just whom she's in love with. Messy love triangle aside, the movie sticks pretty close to the conventions of the romance genre. Boy meets girl. Girl turns down boy. Boy wears girl down, and pretty soon they're smooching on the scenic banks of the Seine.
Movies in the romance genre often throw some sort of wedge between their lovers, too. In An American in Paris, that's Henri. His history with Lise threatens to keep Jerry and Lise apart; she's torn between the heart palpitations she has for Jerry and the sense of duty she has to Henri, who took care of her during the war. Ultimately, Jerry and Lise get their "happily ever after" on, even if, just like a textbook romance movie, it isn't until the very end of the flick.
Drama
Movies in the drama genre are all about conflict, and Lise is one seriously conflicted chick. Should she stick with Henri, her wartime protector who knows her inside and out? Or should she hitch her love wagon to Jerry's artsy star? (Sorry for saying "love wagon," BTW.)
If, like in An American in Paris, your movie's got a twisted love triangle at its core, odds are you're feasting your eyes on a drama. This conflict between the main characters isn't just messy; it drives the whole film's story. Take Henri out of the equation, for example, and you're left with a movie about a dude who sticks around Paris after the war to paint and starts dating a girl who works at a perfume shop. Yawn city, right?
An American in Paris may be a musical—with characters bursting into song left and right and gleefully tap-dancing on pianos—but as a drama, it also reflects reality. Relationships are chaotic and complicated. People fall in and out of love. Sometimes we love people who don't love us back. Sometimes we loan them our personal chauffeur, gift them an art studio, and sit in our fancy hotel room in our sequined ball gown, secretly plotting other ways to buy their love.
Okay, so that last one's probably just Milo, but the fact remains that An American in Paris fits right into the drama genre. It's got tension, conflict, and portrayals of the sloppy, realistic, and sometimes agonizing sides of falling in and out of love.