Colorado and Washington becoming the first states to legalize the recreational use of marijuana prompted speculation Wednesday about Amsterdam-style "drug tourism" and a new round of jokes about Colorado's official state song, Rocky Mountain High.

The Colorado measure limits cultivation to six marijuana plants per person, but "grow-your-own" pot would still be banned in Washington. Both states prohibit public use, and Washington includes a strict "drugged driving" provision for marijuana impairment.

Tuesday's votes are "groundbreaking," said Beau Kilmer, co-director of the Rand Drug Policy Research Center. But since no modern jurisdiction has lifted prohibitions on production, possession and distribution of cannabis for recreational use, he says, "There are two big issues: Do the states want a marijuana tourism industry, and if so would the federal government allow it?"

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