And we now turn to Washington state, which on Tuesday will become the second state to allow the legal sale of recreationial marijuana. Washington follows Colorado, which is six months into its own... See More
And we now turn to Washington state, which on Tuesday will become the second state to allow the legal sale of recreationial marijuana. Washington follows Colorado, which is six months into its own marijuana experiment. ABC's Clayton Sandell now on the law's impact so far in the mile high city of Denver. Have your I.D.S ready. Reporter: Depending who you ask -- We think the whole world is watching right now. Reporter: -- Colorado's legal marijuana experiment either going to bring a harmless new gold rush or plunge the state into reefer madness. Under the influence of the drug he killed his entire family. Reporter: Six months since the first ever recreational pot shops opened here, Colorado is typing out what's working and trying to fix what isn't. $60. Reporter: So far this year recreational marijuana dealers have raked in nearly $70 million giving the state 11 million in new tax revenue. Tourism isn't suffering either. The government still makes a lot of money off of arresting people for this where I live. Reporter: Half of Linda Andrews' customers come from out of state. We're constantly seeing people that are so excited just to be here because they come from someplace that it doesn't exist. Reporter: But with the good comes the bad. Police found a receipt inside the home for pot purchased just three hours before the shooting. Reporter: Two deaths, including one alleged murder, have been linked to overdoses of edible marijuana mixed into cookies and candy prompting new stricter labels and packaging. Very good. Reporter: Dr. Sam Wang says last year eight kids showed up at the children's hospital emergency room with marijuana poisoning. This year already a dozen. When the people decided they wanted to decriminalize marijuana, I think one of the things that people didn't entirely think about was kind of some of these public health concerns. Reporter: Then there are the banks. Businesses can't open accounts because the federal government still considers pot illegal. So while we are legal, we don't always feel entirely legal. Reporter: Heavily armed private security firms are thriving. We look for anything suspicious. Reporter: Hired to move piles of cash from stores to secret vaults. We don't like to say how much our clients have in their store. Reporter: Pot advocates who argue weed is less harmful than alcohol point out overall crime is down, though any connection to marijuana is hazy. The system of regulation is actually safer for the public than an unregulated black market. Reporter: They have been closely watching in Washington state where recreational stores opened this week hoping to avoid the growing pains felt in Colorado. Ganja is ground zero. For "This week," Clayton Sandell, ABC news, Denver.
This transcript has been automatically generated and may not be 100% accurate.