“Film noir” is a hard term to find a definition for. Some film historians argue that the term film noir is a genre while others argue that it is the mood or tone of the movie. Regardless on how you see the definition of a film noir, I believe that Casablanca is a film noir.
If you look at some of the simple characteristics of a film noir, you can easily see that Casablanca is an obvious film noir. For example, an urban environment. The real Casablanca and where the movie is set is in Africa, which makes you think of the jungle or the savannah, but the majority of the film is set in Rick’s Cafe Americain, which is an upscale American bar set in the middle of Africa, so you can tell that the makers of the Casablanca really wanted an urban environment.
Another characteristic is shadows. This film noir has so many shadows that we literally almost wrote a paper about the shadows rather than a paper on weather or not Casablanca is a film noir. Speaking of shadows, an additional characteristic is a flickering street lamp and while there is no flickering street lamp, I’d argue that the spotlight every time they go outside of Rick’s Cafe Americain has the same effect as a flickering street lamp.
One more example is the corruption. Honestly, my favorite scene in the movie (and one of my favorite scenes of all-time) is when Captain Louis Renault closes down Rick’s Cafe, claiming to be “...shocked, shocked to find that gambling is going on in here!” And then immediately is handed his winnings for the night.
An additional example is that in a film noir, the characters are torn by psychological conflict. In Casablanca, Rick is torn because he loves Ilsa Lund but even she is torn in a psychological conflict because she is married to Victor Laszlo. Even though Rick and Ilsa Lund had the few days in Paris together, causing this mess.
Lastly, in a film noir, usually the main character is alienated from everyone else. In the beginning of Casablanca, Rick was the only one at his own bar who was not drinking at all. Rick is also alienated because everyone goes to him. He is a figure with power, causing himself to be alienated to everyone else because he is above them.
I think with all of the examples I have given, Casablanca is an obvious film noir. Casablanca could be argued on the other side but there are more facts and support that it is a film noir. There are even examples that I did not mention that prove that Casablanca is a film noir; for example, just the fact that the film is in black and white rather than color.