Originally Posted by
muji
U.S. passports, until around the early 80s (not sure exactly) were not blue. They were gray.
Google claims they were red from 1926-1941, green from 1941-1976, switching to blue for the bicentennial. They went to green for one year in '93, then back to blue. I had one of the '93-94 greens (Googling, it doesn't appear to be Islamic Green)
EDIT: fwiw,
passportinfo.com agrees.