Let me clarify what I said before. I understand that chorizo is found all over the western world and that many are distinct from each other. The reason for my question is because I can't identify what the root of the difference (cosmetic, it seems) between 2 very similar types of chorizo is. And the color to which I'm referring is the color of the chorizo when cooked. The chorizo in the SW US is red just as those in mexico but the color of the meat when cooked is different. Both types of chorizo also use a lot of ancho chile and vinegar which are the 2 key ingredients (besides the pork obviously). I found that most of the vendors here in LA, SD, and even the Tijuana border also add pequin pepper. Never have I seen annatto listed as one of the ingredients in this region's chorizo though... The SW US version comes out to a be very earthy brown while many times in Mexico, I've seen some retain their blood red color. Oh and heidih, yes, the prepackaged chorizos that I see at stores in LA are made in California but when I check the ingredients list, they always have a food coloring and other additives so I don't find that to be a reliable source though they retain their redness as well...