The government still has many means to slow or stop the marijuana train. And President-elect Donald Trump's nomination of Alabama Sen. Jeff Sessions to be the next attorney general has raised fears that the new administration could crack down on weed-tolerant states 20 years after California became the first to legalize medical marijuana.
"We need grown-ups in charge in Washington to say marijuana is not the kind of thing that ought to be legalized. It ought not to be minimized, that it's in fact a very real danger," Sessions said during an April Senate hearing.
The Controlled Substances Act bans pot even for medical purposes. A closer look at some of the government's options for enforcing it: