Regional varieties?
I'm also thinking that some ranges were regional. I'm basing some of this theory on what I've noticed with typewriters--in the Seattle metro area, of typewriters that came in a choice of red, harvest gold, light blue, and gray, light blue and gray are the colors I'm most likely to find. Similarly, most of the vacuums I've seen, including Eureka and Hoover, are either white, or some shade of blue. So, I'm guessing that most of the Eurekas sold in the Northwest are models that came in blue.