Couple of links for you :
The Blue Star Memorial program is run by
National Garden Clubs, Inc.. Unfortunately, while they have a description of the program, they don't have a list of the roads so designated. (It appears, with a bit more Googling, that if a state's Garden Club affiliate can afford to purchase the sign, and can get the appropriate permission from their state government, then any highway can be a Blue Star Memorial Highway...)
FHWA also has a page on the Blue Star highways, but again, no list.