Blues scholars are happy to oblige when asked to get more specific on certain subjects. Take the theme of Texas blues, but bring a big plate to the buffet, please. Rob Cooper was not only a great Texas blues pianist, he represented a much more distinct style of playing not only from the state, but within the city of Houston as well, which in the early '30s was hardly the sprawling metropolis it would become half a century later. What is known as the Texas Santa Fe style of piano is not the result of a badly assembled map, but like many musical genre terms, a reference to local...