Interesting. It was all over the place in CA, and is even here in potatoho (at least my part, as we have a lot of Mexican ag workers). In fact I think I might have some in the cupboard from the last time my Mexican nephew in law was here and bought some at the local grocery.
I remember having it years ago somewhere, not sure if it was at a restaurant in WY or CO, but it was someplace out west.
My lady friend's neighbors at her place in Mexico are from LA and they bought a place in Mexico like my lady friend did. They are 2nd or 3rd generation Mexican and had family ties to the area in Mexico. They had us over for drinks the first night I was there, and they had various cut up vegies, like cucumbers, tomatoes, raddishes and container of Tajin next to it. He said sprinkle a bit of this on the veggies, it's super popular in LA. I remembered the taste from an earlier experience as mentioned above.
Last weekend, I was at Wal-Mart and I was buying some stuff to make Texas Caviar for an afternoon bar potluck and I saw the Tajin in with the canned green chilies. So bought some it.
Also scored a bottle of Salsa Huichol Picante which is pretty tasty hot sauce.
I can't wait to make Micheladas too.