Total marijuana demand in Colorado, where the the United States' first recreational pot shops opened in January, is estimated at 130 tonnes this year, a study for the state's revenue authority has said.
A day after Washington became only the second state to allow recreational sales of the drug to adults, the report said the projected demand in Colorado was much higher than anticipated.
More than 90 per cent of it came from residents, while out-of-state visitors accounted for only about 9 tonnes.
"The primary difference is caused by much heavier dosage amounts consumed by the state's 'heavy user' population - those who consume marijuana on a daily basis," said the report, prepared for the Colorado Department of Revenue.
It said tax figures showed that the retail supply of marijuana was growing in the state, while supply via medical marijuana dispensaries had remained relatively constant.
"The retail demand is derived primarily from out-of-state visitors and from consumers who previously purchased from the Colorado black and gray markets," the report said.
And it estimated that out-of-state visitors currently accounted for about 44 per cent of retail sales in the Denver metro area, compared with about 90 per cent in mountain resorts.