Rockmount is an authentic western-wear company out of Denver, Colorado.
Here are some Rockmount shirts:
Bob Dylan on the cover of the Rolling Stone wearing a Rockmount shirt:
The website: https://www.rockmount.com/
Flint And Tinder:
Uses Supima for their t-shirts and briefs. Supima is a top quality hybrid (that means cotton plant on cotton plant, not GMO) Made In USA
"We use NO GM cotton in any of our products (Iron Heart)." made with U.S. long staple cotton.
Pure Blue Japan:
"Our cotton is not genetically modified (Pure Blue Japan)."
The Strike Gold:
Freely shares denim with Pure Blue Japan (PBJ never uses GMOs) and also uses rare and fine cotton...
Reigning Champ X Everlast N.Y.
The devil is in the details:
Reigning Champ X Everlast N.Y. Review:
The craftsmanship is impeccable. Super thick poly stitching. Hefty/dense/soft cotton fabric. Thick ribbed fabric at side seams, collar, and very bottom with a bit of elastic. Nice shiny pitch black color. Screen printing is really well done. Everything on it feels rugged with no weak points or neglected...
According to the website: "The organic cotton was grown in Helm, California."
Also, though California is extremely dry it has some rather amazing aqueducts: http://en.wikipedia.org/wiki/California_Aqueduct
PuraKai is a nice little company out of San Diego that makes clothing from high-quality natural materials.
I got a couple of shirts from PuraKai and I'm very pleased with the quality. They are made in California from locally grown organic cotton which is super cool. They are extremely comfortable shirts too! Perfectly breathable for summer. I believe PuraKai uses Pima cotton.