From an AP report at the link below:
It took 50 years for American attitudes about marijuana to zigzag from the paranoia of "Reefer Madness" to the excesses of Woodstock back to the hard line of "Just Say No."
The next 25 years took the nation from Bill Clinton, who famously "didn't inhale," to Barack Obama, who most emphatically did.
And now, in just a few short years, public opinion has moved so dramatically toward general acceptance that even those who champion legalization are surprised at how quickly attitudes are changing and states are moving to approve the drug — for medical use and just for fun.
Full report here.