Cold weather probably played a bigger role in bringing back the hat, but sadly, the hat common to New Jersey guidos, South Carolina rednecks, Idaho potato farmers and Los Angeles gang bangers is the ubiquitous 'tractor hat,' which is derived from the cheap baseball style cap with the adjustable plastic tab.
A word about blue jeans, which, when I was growing up, were called dungarees, one of the more unfortunate marketing ideas of our time: Starting as a work garment for miners, the ubiquitous blue jeans became a staple of the counterculture starting when Brando wore them in 'On the Waterfront' and remained so through the anti-war protests of the '70s.