Cannabis use amongst adults in California has remained largely stable since 2017, when the US state legalised retail sales, according to a study published in the Journal of Cannabis Research.
Researchers from the University of California, San Diego, analysed data from 178,836 adults surveyed between 2017 – one year before retail sales began – and 2024. They found that past-month cannabis use rose briefly from 14.5% to 17.7% in 2018, but returned to 15.4% by 2024, showing no significant difference from pre-legalisation levels.
“Prevalence of past-year and past-month cannabis use among adults in California remained largely stable across the eight-year study period spanning the onset of retail availability of non-medical cannabis products,” the researchers wrote.
However, the study identified notable shifts in how Californians consume cannabis. Combustable methods such as smoking joints, pipes and bongs declined significantly from 71.2% to 58.1%, while edible consumption increased from 40.3% to 53.6%.
The data also showed that there had been a change in the demographics of cannabis consumers during the period since legalisation. Past-month use among adults aged 40 to 59 increased from 10.7% to 14.5%, and more than doubled among those aged 75 and older, rising from 2.4% to 5.5%.
In contrast, use among young adults aged 18 to 25 showed no significant change – a finding researchers described as offering “some reassurance that legalisation and retail availability have not been accompanied by increased use in this vulnerable subgroup”.
The study authors noted that there may be a unique explanation for the lack of dramatic change. “Cannabis was already widely accessible in California through long-established medical and illicit markets, so past-month use among adults was already common, leaving comparatively little room for further increases.”
The findings showed that frequency of use also remained consistent, with consumption concentrated at the extremes – roughly 40% of users reported consuming cannabis one to five days per month, whilst 37% used it 20 to 30 days or more.
Dispensaries remained the primary source of cannabis for users, accounting for approximately 77% of procurement, another figure which remained stable throughout the period studied.
The study is the latest to show that allowing adults legal access to cannabis does not increase adolescent consumption. Research recently conducted by the German Federal Institute of Public Health found that cannabis consumption among 12 to 17-year-olds remained stable after the country partially legalised cannabis. Survey data from the American state of Minnesota published earlier this year revealed that fewer young people were using cannabis following the state’s legalisation of recreational marijuana for adults in 2023.
