Definatley Film Noire!
This movie is definatley a Film Noire. I've read several articles and there seems to be alot of debate about if ''Niagara'' can be considered a Film Noire or not. I have to assume that anyone saying it's not is trying thier hardest to ignore all the blatant noire elements the picture contains. To illustrate my point, here are just a few things off the top of my head that suggest this is a film noire.
1) Use of Mirrors. When Rose Loomis is talking on the telephone to tell her lover that the time is right to kill George, the mirror is very obviously used to show her duplicity.
2) Rose's Manipulation. The scene in which she plays the record - ''Kiss'' - in order to provoke George's outburt is pure Noire. In particular, the facial expression Monroe pulls at the point of his outburst is VERY noire.
3) Intense Lighting. You'd have to be a fool not to pick up on this. The lighting is used extensively to promote the Film Noire look. Window Blinds (typical Noire) are used all the way through the movie. The shadow that Rose casts on Polly - reinforcing her status as a femme fatale - is another example but shadow is used throughout.
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4) The climactic scene in the belltower - in which Geroge tracks down Rose and kills her absoloutley SCREAMS Noire. Look at the lighting at the end of this scene - especially the high angle looking down on the action. The tension-filled soundtrack and the strong feeling of Rose getting ''closed in'' and of ''entrapment'' are other sincere nods towards Noire.
Puritans are going to say it's not in Black and White, and so ''Niagara'' is simply not a true Noire but I simply can't agree. Furthemore, I believe very sincerely that it was even an influencial movie to ''Vertigo'' by Hitchcock - you can see the simmilarities very clearly. I know the plot is a bit thin and perhaps any Film Noire elements within it are often superficial but I still class ''Niagara'' as a true Film Noire - and a bloody good one at that.