DENVER (AP) -- Dignitaries from three nations are wrapping up a "Weed 101" tour in Colorado to learn about a regulated marijuana market.
The visitors from Canada, Mexico and Uruguay gaped at a greenhouse full of pot plants tagged with digital markers. They learned about video surveillance and measuring drug production. They saw marijuana turned into tinctures, pills and skin patches, and met with state regulators.
The three-day tour wrapped up as Colorado prepares to play host to 1,000 drug policy experts and legalization backers at the International Drug Policy Reform Conference taking place through Saturday.
Marijuana legalization will be a major topic after Colorado and Washington state authorized marijuana possession for all adults over 21, with retail sales beginning next year.
Other nations considering new drug policies are watching.