Courts in Kansas City, Mo., can impose a maximum fine of $25 for possession of up to 35 grams of marijuana, after voters embraced a ballot initiative Tuesday. Here, three grams of marijuana is displayed. Oliver Contreras/For The Washington Post via Getty Images hide caption
For three years recreational pot has been legal in Colorado, but using it in public is still against the law. That will change this summer when pot cafes are slated to open. Brennan Linsley/AP hide caption
A demonstrator at a marijuana legalization rally in Washington, D.C., on Inauguration Day 2017. Theo Wargo/Getty Images hide caption
The highly rated variety of medical marijuana known as "Blue Dream" was displayed among other strains at a cannabis farmers market in Los Angeles in 2014. Frederic J. Brown/AFP/Getty Images hide caption
Los Angeles residents awoke on New Year's Day to see the iconic Hollywood sign altered to read "Hollyweed." Most of them were fine with it. Damian Dovarganes/AP hide caption
Researchers have found marijuana metabolites in the urine of babies who were exposed to adult marijuana use. deux/Corbis/Getty Images hide caption
Marijuana is now legal for recreational or medicinal use in more than half the country, but it's still banned in professional sports. Jack Guez/AFP/Getty Images hide caption
Alabama Sen. Jeff Sessions at Trump Tower in New York City on Thursday. Many in the multibillion-dollar marijuana industry fear what his nomination for attorney general would spell for business. Drew Angerer/Getty Images hide caption
Shane Cavanaugh, owner of Amazon Organics, a pot dispensary in Eugene, Ore., arranges the cannabis display in his store in September 2015. Ryan Kang/AP hide caption
Is marijuana a gateway drug to smoking cigarettes? PhotoAlto/Katarina Sundelin/Getty Images hide caption
Krystal Xiques smokes marijuana at a rally in support of Prop 64 at Sparc Dispensary in San Francisco on Tuesday. Marcio Jose Sanchez/AP hide caption
A marijuana plant is displayed during the 2016 Cannabis Business Summit & Expo on Jun. 22 in Oakland, Calif. Justin Sullivan/Getty Images hide caption
Marijuana grows in the home of two medical marijuana patients in Medford, Ore. Jeff Barnard/AP hide caption
Libertarian presidential candidate Gary Johnson talks to a crowd of supporters at an August rally in Salt Lake City. George Frey/Getty Images hide caption