Here is a large "Patrolled by Aircraft" sign on US101, near
Wildhorse Road. This is taken 9/6/2001. I don't recall seeing similar
signs on
I5 or 99. This sign has been up since at least the mid 1980s.
This is a close up of a sign assembly on 152 East in Los Baños,
California, showing signs for 165 and I5. California's Green Miner's
spade is more highly regarded by most highway fans than most state
highway shields. After all, quite a few California highways are up to
interstate standards. This photo courtesy Trevor Carrier, from the
Summer of 2006.
This sign photo was taken on slides in July 1986. I think this
"Expressway Entrance" sign was up until about 1996.