Thursday marks marijuana culture's high holiday, 4/20, when college students gather — at 4:20 p.m. — in clouds of smoke on campus quads and when pot shops in legal weed states thank their customers with discounts. This year's edition provides an occasion for pot activists to reflect on how far their movement has come, with recreational pot now allowed in eight states and the nation's capital, as well as a changed national political climate that could threaten to slow or undermine their cause/Associated Press. More here.