"Over the past several years, the nation has seen an uptick in the use and abuse of opioids--both prescription opioids and non-prescription opioids such as heroin. In 2016, there were an estimated 948,000 individuals (0.4% of the 12 and older population) who reported using heroin within the past year--up from 0.2% to 0.3% of this population reporting use in the previous decade. In addition to an increase in heroin use over the past several years, there has been a simultaneous increase in its availability in the United States. The increase in availability has been fueled by a number of factors, including increased production and trafficking of heroin--principally by Mexican criminal networks. Mexican transnational criminal organizations are the major suppliers and key producers of most illegal drugs smuggled into the United States. They have been increasing their share of the U.S. drug market--particularly with respect to heroin--even though the United States still receives some heroin from South America and, to a lesser extent, Southwest Asia. To facilitate the distribution and sale of drugs in the United States, Mexican drug traffickers have formed relationships with U.S. gangs."
CRS Report for Congress, R44599
Congressional Research Service: https://crsreports.congress.gov/