In the '60s and '70s, Colorado was a jewel in the crown of hippiedom. Communes popped up, granola and grass were available — and then there was the regional capital, Boulder. Is it why we were the first state to fully legalize marijuana? Maybe — but one thing is certain: It launched Denver's alternative art scene, which is still going strong. In 1979, a bunch of Boulder bohemians rented a storefront in northwest Denver that became Spark Gallery, the city's first artist cooperative, and in the intervening decades, those kids with disheveled hair became veteran artists. RetroActive: Founding Spark recalled those early days; it was presented at Pirate: Contemporary Art (another early co-op that opened right after Spark) and mounted by Rule Gallery — precisely the kind of community-mindedness the hippies promoted. Among those included in the show were Clark Richert, Jerry Johnson, Richard Kallweit, Charles DiJulio, George Woodman, Andy Libertone, Paul Gillis and Margaret Neumann. Denver's vibrant contemporary-art world of today owes a big debt of gratitude to this groovy crowd.