[sodly]

Back in the 50s west coast trucks (semis) were allowed, by law, to be a lot longer overall length than the east coast trucks. The length laws were much looser out west. So west coast trucks often had very long wheelbases. You see this in a lot of early Peterbilt and Kenworth trucks vs. Mack or Autocar trucks, for example. I presume west coast mirrors were necessary just to be able to see all of the trailer that was so far behind the cab. Amazingly, a lot of old tractor-trailers in the 50s still only had tiny mirrors like the stock ones on a Chevy c10, maybe 6" round. That must've made life interesting!