In terms of what is meant by the spirit of a given decade, I leave that up to you. I’m also thinking generally about American movies representing American decades but feel free to pick different experiences. The only rule is that the movie should be made relatively contemporary to the decade the it captures (but you can cheat a bit like I did with the Grapes of Wrath) . So You can’t use the Great Gatsby to embody the 20’s. I’ve attached my picks but since I’m not a movie or historical culture buff I’m sure you all can do better
1910’s The Immigrant (1917)
1920’s Lights of New York (1928)
1930’s Grapes of Wrath (1940)
1940’s The Best Years of our lives (1946)
1950’s The Blackboard Jungle (1955)
1960’s Easy Rider (1969)
1970’s Saturday night fever (1977)
1980’s Wargames (1983)
1990’s Clerks (1994)
2000’s Rendition (2007)
2010s (too soon)
A few comments. I went with Best Years of our lives for 1940’s because although it was about the war it it wasn’t a war movie and concentrated on the experience back home. I chose Black Board fever rather than Rebel w/o a cause because IMHO you can’t have a 50’s movie without rock and roll, and also the racial elements the was underlying society at the time. There are lots of options for the 80’s I chose War Games because it both captured the Cold war as well as video games and the advent of the PC.