According to ConnDOT's sign catalog, it appears they don't color them anymore, as can be seen on pages 85 - 92. I also looked around for an SCDOT catalog for the South Carolina inconsistencies, but unfortunately I couldn't find any manuals on their website.
Congrats guys, we did the lower 48! I figure I may as well top off Alaska and Hawaii to make the lot!
Alaska!!!
Alaska uses A white square with the bigger dipper constellation and the north star, with ALASKA in the top right corner. The same shield is used on both Highway and standalone signs
Gantry:

Roadside:

Roadside:



Hawaii!!!
Hawaii's sign is similarly shaped to California's, but with a rounded bottom. This one doesn't widen when larger numbers are used.
Gantry:


Roadside:

Roadside:

THAT'S ALL 50!!!!!