Originally Posted by
chephy
Typically it is legal where no other reasonable routes exist. That usually is in the not-too-densely populated places. Apparently, there are long and quite pleasant stretches of interstate along the U.S. West Coast where cyclists are allowed, and lots of touring cyclists use them.
I'm in SoCal and usually ride HWY 1 (Pacific Coast Highway) at least once a week and HWY 101 occasionally. There are sections where, as cephy noted, don't have reasonable alternatives so are legal. Never really had any issues riding either except having to patch a couple of tubes once on 101. Tough to find pin holes with all the big trucks blowing by.