Tex-Mex food has been a topic of conversation around my office quite a bit lately. What's the difference between Tex-Mex and Mexican foods?
This question could produce heated debate in some areas of the country, but it seems that most sources agree on a few key points. The term "Tex-Mex" has been around for a while, but it really gained popularity in the 1970s, when Diana Kennedy published The Cuisines of Mexico (now available in a reprint combining two of her earlier books) and tried to show tortilla-chip-loving Americans a more full range of Mexican dishes. Tex-Mex was used to refer to the many Mexican restaurants all over Texas serving Americanized versions of Mexican food.
So what does distinguish Tex-Mex from Mexican food? This is a more difficult question, and it's usually answered by looking at ingredients used in Tex-Mex that are less common in more authentic Mexican food. Cumin, for instance, is not used nearly so widely in Mexico as in Tex-Mex. Meat is more common in Tex-Mex too. Maybe the largest factor is starch - the abundance of nachos, tacos, and tortilla wraps are simply not as common in Mexican cuisine as Tex-Mex may lead you to believe.
Both styles have their advocates, of course - although it's worth noting that even Tex-Mex fans disavow Taco Bell.
• Mexican and Tex-Mex food at the Food Timeline