American food contains maize, obviously. This works for multiple understandings of the word "American" :)

Pretty much, but not exactly. There is also a cooking technique (so American will be deep-fried).

Most national dishes are nothing more than adaptation of dishes from another country. Sometimes tweaks to ingredients, sometimes tweaks to techniques.

American food = contains corn (maize), in all its glorious (ex. nixtamalized, unprocessed, flour, etc.) and unholy (ex. high fructose corn syrup) forms.