woodstock. more than half a million people traveled to bethel, new york, to take part in one of the defining events of the 1960s. obvious transition here, perhaps. washington state and colorado legalized recreational marijuana use in their states last year. but putting the laws into practice has been anything but smooth sailing. with pot still illegal on a federal level, there are a number of hurdles, including how to regulate the marketplace. cnbc's jane wells with more on the challenges ahead. >> craig, welcome to the mile high city. this is legal medical cannabis. you still can't grow or sell recreational pot yet, but it's coming. in the meantime, no matter how you get your pot, if you got 'em, you can smoke 'em. either here in colorado or in washington state where these pictures were shot. if you're at least 21 years old,