Travelers leaving from the Colorado Springs Airport have done a good job of stashing their marijuana at home or in their cars before they fly.
Amnesty boxes, added to the airport in January, have been sparsely used for marijuana, said Sgt. Matt Harrell of the Colorado Springs Department airport unit.
"I think people know," he said. "They haven't been trying it."
While some travelers have dropped off edibles, marijuana vapor cigarettes and grams of marijuana, he said those aren't the most common items.
"What we've gotten more than anything is unused prescription medication," Harrell said.
Since the 2012 passage of state Amendment 64, which allows people 21 years and older to use or have recreational marijuana, and the official implementation of the law in the state this year, agencies, organizations and law enforcement officials have had to adapt to the change.
With federal law prohibiting marijuana - and having jurisdiction over airplane travel - confusion can emerge where state laws differ.
The amnesty boxes give passengers a last chance to ditch anything that might be illegal before going through security and possibly facing consequences.
The Transportation Security Administration, which screens airline passengers and their bags, will call Colorado Springs police if a passenger tries to take marijuana onto a plane.
Denver International Airport does not have marijuana amnesty boxes, a spokesman for the airport said. Airport personnel ask people to throw it away, he said.
In addition to marijuana and prescription drugs, Harrell said other items, such as water bottles and cigarette butts, are found when the boxes are checked once a month.
"Probably gummy bears are the strangest thing we've seen in there," he said.