Airports in Denver, Las Vegas and Reno, Nevada, don’t allow pot on the premises—but Los Angeles International—the world’s fifth-busiest airport—now allows customers aged 21 and over to bring marijuana, a policy change made to accord with California law on personal consumption of the drug. So do the two largest Pacific Northwest airports: Sea-Tac and Portland International, which follow state laws in Washington and Oregon, respectively. The law in Oregon even allows travelers to carry marijuana on flights within the state—even though airlines prohibit pot.

“It’s a tangled web, for sure,” said Dave Bannard, an attorney with Kaplan Kirsch & Rockwell LLP in Boston, who consults with airports on marijuana and other regulatory issues. “Airports are having to come to grips with this in a way that nobody expected a few years ago.”

Regardless of the airport, your personal pot isn’t allowed beyond the security checkpoint, a federal zone where marijuana of any amount—irrespective of a medical purpose—remains illegal.