A political arm of the alliance spent more than $1.6 million as one of the main funders of the Washington state campaign.
The passage of the ballot measures in Colorado and Washington state in November allowed personal possession of the drug for people 21 and older. That same age group will be allowed to buy the drug at special marijuana stores under rules set to be finalized next year.
No other states have legalized marijuana, America's most widely used illicit drug, for recreational use. The drug remains illegal under federal law. Connecticut and Massachusetts also approved medical marijuana in 2012.