Washington state authorities have received applications for 3,746 marijuana business licenses, including 867 retail licenses, according to The Seattle Times newspaper, which urged caution in an editorial.
"Legalization of marijuana (is) a seismic change in drug-control policy, perhaps the biggest since the end of alcohol prohibition. Supporters and skeptics need to take a deep breath," it said.
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Colorado's branch of the National Organization for the Reform of Marijuana Laws (NORML) said everyone will benefit.
"It will mean jobs, tax revenue for the state and local jurisdictions, increased tourism, and a developing progressive new industry in Colorado," NORML attorney Rachel Gillette told AFP.
"It will also have an impact in that marijuana sales will be brought out of the shadows and the black market," she added.
Michael Elliott, head of the Medical Marijuana Industry Group, noted that Colorado has licensed medical marijuana businesses since 2010, but said the influx of tourists for recreational use of pot could lead to shortages.