I found this really interesting article today on why Texans have always celebrated Cinco de Mayo, and perhaps why all Americans should as well (the French siding with the Confederacy - really? Wow). The connections to Texas that the article outlines are many: not only was the Cinco de Mayo hero Ignacio Zaragoza born in Texas, but Tejano volunteers went to Mexico to help defeat the French. When they returned, they started the tradition of celebrating this day back here in Texas. As Instapundit is fond of saying: read the whole thing.
I know the celebration of Cinco de Mayo is a new (and perhaps a marketing-fueled) event in most other parts of the US, but here in Texas, it's just another part of our history, too.
Happy Cinco de Mayo, y'all.