The 70s are widely regarded as one of the best decades for film, especially American film. As a result, there were many viable candidates for this list. You may balk at the exclusion of certain titles, but I had to go with my honest gut feeling. As always, feel free to debate my choices in the comments section.
#11-20 (in alphabetical order)
All The President's Men
Kramer vs. Kramer
Willy Wonka & the Chocolate Factory