[lentulusgracchus]

Actually, the design was seen in all theaters, including Texas, where the cavalry troops of Gen. Jo Shelby, refusing to surrender, retreated south across the Rio Grande, sinking their colors in the river rather than surrender them. One color sergeant, while the column was encamped in Mexico, went back and retrieved his color, and that flag is kept in Texas today. It was a standard-issue 13-star cavalry-cut CBF with a taped border and gold fringe.

Many similar have been preserved from all areas of the war, some with subtle variations (2:1 proportions, hexagonal heraldic stars vs. 5-pointed "mullets" [stars]; Cross of St. George w/ reversed colors vs. Cross of St. Andrew [Gen.Polk was an Anglican bishop], and so on.) and some of completely different design. There was even one cavalry color carried in Texas that was nothing but a Scottish saltire with unit cachets and honors added.

[Vanders9]

Oh I’m not saying it wasn’t used in other theaters - I’m sure it was, it’s just that it was MOSTLY used in the eastern one. Its popularity now is almost entirely based on its association with the Confederacy’s premier military formation (the ANV) and the fact that it is just about the best widely used design, much better than the “stars and bars” for example.