Food in the United States varies by region. The US is typically broken up into 5 main parts. Western, Mid/Southwestern, Northeastern, and Southern. I grouped the South and Mid West together as this is where the Cowboy culture exist (especially in the huge state of Texas).
The Western USA still carries its Mexican and Native American food culture proudly. A coastal region, fish is a major part of the cuisine. Also, food from this region showcases a lot of strange and delicious plants that some people may not even know are edible. Grilled cactus, fish tacos, a variety of corn dishes and authentic Mexican cuisine are found here.
Northeastern USA is influenced by English, Scottish, Irish and Scandinavian cultures. Germanic speaking people immigrated here during the waves of first settlers who came to the New World and they brought with them their food culture. Meat/fish Pies, gruel of all varieties, creamy meat dishes, and sweet pastries were brought to these lands first and are still very popular there.
Mid/Southwestern USA is also heavily influenced by Germanic people. Texas in particular is a state that has absorbed both western and southern food culture. Beef cattle and plains ranchers provide a lot of the meaty ingredients for these recipes. Texas is the origin of cowboy cuisine and Tex-Mex.
Southern USA is the home of soul/comfort food. In this area food is French and Spanish influenced (what is identified as Creole and Cajun). Because of slavery during the pre-Civil War era, many cooks were African and Caribbean. Southern food is heavily influenced by all these cultures that has been fused into something fairly new and unique.
Along the east and west coast immigrants from all over the world have settled in the largest numbers. In huge Metropolitan cities such as New York (east coast) and Los Angeles (west coast), you can find authentic cuisines from all over the world.