A colorado tux is a blue blazer over a button down long sleeved oxford shirt on top, and jeans and cowboy boots beneath that.
The blue blazer can come from any department store; the oxford has to be 100% cotton, and pressed; ideally the jeans would be Wrangler, because that's what real Colorado cowboys wear; and the cowboy boots have to be pointy, and can't be one of those new fangled pairs with laces.
It can be accessorized with a wide brown leather belt, hopefully with leather stitching along the edges, and with a big shiny rodeo belt buckle. A cowboy hat of any kind is also a good accessory.
At the opera in Denver: "Look at all the Colorado tuxedos. That's about as nice as people dress around here."
Wearing nothing but soft shell outdoor clothes, including jacket, pants and hat. Accessories often include Oakleys, ponytails, Subarus, Border Collies, climbing tape, Tibetan prayer flags and "Yo Bro" accents.
"Look at that douche in the next campsite, he's got a total Colorado Tuxedo on."
"Yeah, his Border Collie wouldn't stop barking last night. I think it's name is Denali."
"Of course, his car has Colorado plates."