The state of California is now the nation's largest state to allow sales of recreational marijuana.
Starting Monday, the state legalized the sale of pot for recreational use for anyone 21 years of age or older.
Roughly 100 shops have managed to get their state licenses so far, and over 1,000 establishments license applications are still pending.
State and local governments expect sales to bring in $1 billion in tax revenue each year.
As more people have access to cannabis, California Highway Patrol officers are warning of an increased risk of pot-impaired drivers on the road.
"You can look at the states that have legalized it and they've seen an uptick in collisions and fatal collisions, so it's definitely a concern for us," CHP Officer Jonathan Sloat told ABC News.
A new poll shows only 40 percent of Americans believe pot contributes to more crashes, but Officer Sloat says the effects of marijuana are obvious.
"What we see behind the wheel is the same thing we see with alcohol," Sloat said. "We see an inability to maintain your lane, maintain a consistent speed. Slow reaction time."
Under the new law, shops will be able to sell without full regulatory controls for six months but will eventually only be able to sell pot tested for potency, pesticides and other contaminants.