U.S. Border Patrol agents report seizing smaller quantities of marijuana along the U.S.-Mexican border since the drug was legalized in Colorado and Washington state, Time reports. In 2011, agents seized 2.5 million pounds. Last year, they seized 1.9 million pounds.

The Mexican army has reported a 32 percent decline in marijuana seizures from 2013 to 2014, the article notes.

“It is no surprise to me that marijuana consumers choose to buy their product from a legal tax-paying business as opposed to a black market product that is not tested or regulated,” Tom Angell, Chairman of Marijuana Majority, told the magazine. “When you go to a legal store, you know what you are getting, and that is not going to be contaminated.”

ArcView, a cannabis investment and research firm, estimates revenue in the United States from recreational drug stores and medical marijuana, which is legal in 23 states, will top $4 billion by 2016.

At the same time that marijuana seizures have declined, violence has also decreased in Mexico—from almost 23,000 murders in 2011 to 15,649 last year. Experts are debating how much of the decline is due to marijuana legalization in the United States. They note the level of violence in Mexico is still high.

Mexican drug cartels continue to make billions of dollars smuggling hard drugs, including heroin and crystal meth. Seizures of both drugs have increased as marijuana seizures have declined. U.S. agents seized a record 34,840 pounds of meth last year.