Colorado has made more than $1bn (£789m) since it legalised marijuana in 2014, with more than 41,000 people now licensed to work in the industry.

It is the latest milestone for the state which has been home to more than $6.5bn in total cannabis sales since legalisation.

April, which includes the annual marijuana celebration 420, and May this year were the two highest-grossing months in the five-year history of the industry. Sales reached a peak of $24.2m in April, with May's figure being $23.9m.

Demand has been steadily growing, with the state's revenue growing from $500m to $1.02bn in just under two years - while getting to $500m took three-and-a-half.

In February 2014, the first month with sales data, the state's total tax and fee revenue was $3.5m. Since July 2017 that monthly figure has not dipped below $20m. Although that does include a rise in the sales tax on cannabis from 10 to 15 per cent that kicked in that month.

Where is cannabis legal in the US? Show all 11 1 /11 Where is cannabis legal in the US? Where is cannabis legal in the US? Alaska Recreational cannabis use was made legal in Alaska in 2014 Getty Where is cannabis legal in the US? Washington Washington was among the first states to legalise cannabis in 2012 Getty Where is cannabis legal in the US? Michigan Recreational cannabis use was made legal in Michigan in 2018 Getty Where is cannabis legal in the US? Massachusetts Recreational cannabis use was made legal in Massachusetts in 2016 Getty Where is cannabis legal in the US? Colorado Colorado was among the first states to legalise cannabis in 2012 Getty Where is cannabis legal in the US? Vermont Since January 2018 it has been legal to posses up to one ounce and two cannabis plants in Vermont. Commercial sales are not legal Getty Where is cannabis legal in the US? California Recreational cannabis use was made legal in California in 2018 Getty Where is cannabis legal in the US? Illinois Recreational cannabis use was made legal in Illinois in 2019 Getty Images Where is cannabis legal in the US? Oregon It was made legal in Oregon to possess up to one ounce of cannabis in 2014 Getty Where is cannabis legal in the US? Maine Recreational cannabis use was made legal in Maine in 2016 Getty Where is cannabis legal in the US? Nevada Recreational cannabis use was made legal in Nevada in 2016 Getty

Illinois recently became the 11th US state to approve cannabis for recreational adult use, the law is due to go into effect in 2020. It joins a list including California, Maine, Massachusetts, Oregon, Vermont, Michigan, Nevada and Alaska. Washington DC also allows legal marijuana sales, while more than 30 states .

In light of this, Colorado Governor Jared Polis said the state "can't just rest on our laurels".

“Today’s report continues to show that Colorado’s cannabis industry is thriving, but... We can and we must do better in the face of increased national competition. We want Colorado to be the best state for investment, innovation and development for this growing economic sector,” he said in a statement.

Colorado has 2,917 legal marijuana businesses, with says some of the money raised by the state goes towards youth prevention efforts and behavioral health treatment. Money has also been spent on funding research into the effects of marijuana use.

Not every state has been able to be so positive about the marijuana economy. California cut its projected tax revenue from the industry by $223m last week.

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The state projects its 15 per cent cannabis tax on the purchase of marijuana products will pull in $288 million for the year that ends in June, and $359 million in the year ending June 2010. That is a reduction of $67 million and $156 million respectively from budget forecasts issued in January.

Governor Gavin Newsom has repeatedly said it would take between five and seven years for the cannabis industry to mature, but sales are being hit by a strong illegal market in the state.