Recreational pot is now allowed in eight states and the nation's capital. For activists, a changed national political climate threatens to slow or undermine their cause.
The Trump administration gave its strongest indication to date of a looming federal crackdown on recreational marijuana, even as a solid majority of Americans believe it should be legal.
Regulators in the 23 states where medical or recreational marijuana is allowed are having a tough time making sure pot buyers don't ingest harmful pesticides.
The legalization of recreational marijuana in two states and medical marijuana others has raised concern that there will be more drivers stoned behind the wheel.
Studies of marijuana's effects show that the drug can slow decision-making, decrease peripheral vision and impede multitasking, all of which are important driving skills.