The Americana Pattern was a limited edition pattern in the Design A Horse program for 2013. It was available with the dark blue shown, with red highlights in the shaded areas, but any color could be ordered with any markings except for the extreme high whites. It is suggested to use the dark blue color as it better promotes some of the more obscure dark stars.
Same or similar to the Star Pattern: https://www.stonehorseref.com/node/60269.