In an article published by The Journal of the American Medical Association, researchers said there was no increase in marijuana use in the general population or among previous users when it became legal where they lived.
The study asked 830,000 Americans over the age of 12 about their cannabis use, before and after it became legalised in their home state.
It looked at data from 2008 to 2017.
Washington state and Colorado, which became the first two US states to legalise recreational cannabis use in 2012, saw a slight increase in usage among white and Hispanic study participants.
And they found that there was no change in cannabis use among individuals aged between 12 and 20 in the states where it had become legal.
Currently 18 states and Washington DC have legalised cannabis use for people aged over 21, and in 20201 alone, Connecticut, New Mexico, New York, and Virginia have legalised the drug.
But a leading animal charity has warned that dogs are getting ill more often from edibles they find on walks.
The American Society for the Prevention of Cruelty to Animals says that calls to its poison hotline suggest that marijuana toxicity in dogs has increased with the number of states where it can be legally sold.
Most of those calls are from cannabis edibles found at the owner’s home, but an increasing number are from drugs found on walks in the “wild”, according to The Los Angeles Times.
While individual states have chosen to legalise cannabis use, there is still a long way to go on the federal level.
President Joe Biden said earlier this year that there needed to be more research done on the impact of legalisation before he could fully support it.
US Senate Majority Leader Chuck Schumer has said he wants to see a bill introduced, even if the president is not fully behind it.
“I want to make my arguments to him, as many other advocates will. But at some point, we’re going to move forward, period,” he said in April.