Thirty states and the District of Columbia have legalized some form of marijuana.
While most states have approved medical marijuana, at least eight states and the District of Columbia have gone further and passed laws that allow recreational use of the drug.
There's some evidence that cannabinoid oils and forms of cannabis can be effective in treating certain forms of epilepsy, nausea induced by chemotherapy, and some other ailments.
But that doesn't mean it comes without risks.
What are some of the risks?
Using marijuana before driving increases the risk of an accident, which would seem obvious to most.
In states where marijuana is legal, "there is increased risk of unintentional cannabis overdose injuries among children," according to the National Academies of Sciences and Engineering 2017 report.
Scientists have linked smoking pot with strokes and diabetes, and evidence suggests that it can trigger a heart attack.
Smoking pot has been linked to chronic bronchitis and chronic cough.
Marijuana use impairs memory, learning, and attention after its use. Limited evidence suggests that cognitive impairments remain in people who stop smoking pot. THC, a chemical in marijuana, disrupts nerve cells in the brain.
Studies linked low birth weight babies to women who use marijuana while pregnant. Long-term effects of the children born to mothers who used the drug are still unclear.
There's not enough data to understand the full effect of marijuana on the immune system, but some evidence shows that exposure to the smoke may cause an anti-inflammatory response.
Links between lung, head, and neck cancers and smoking pot haven't been proven, but it could be because of research limitations.