Billboard on left appears to say "Elliotts Fashion Center - Womens - Misses - Juniors". Billboard on right appears to be for "DX Gasoline". The middle billboard is hard for me to make out, but I believe it may be for "Old Milwaukee" brand beer. All have additional text that I am unable to read.

Old Milwaukee Beer -- 'Brewed for that wonderful world of leisure'. DX Super Boron Gasoline - DRIVE A CAR THAT'S ALIVE!