On its own, it was an impressive haul, but in the wider picture, it was just a drop in the bucket: On Sept. 26 at a checkpoint in Sarita, Texas, U.S. Border Patrol agents seized 64 kilograms (142 pounds) of methamphetamine with a street value of $4.5 million. A methamphetamine seizure of this size is not surprising or unusual, especially in this location, given that cartels in Mexico manufacture the drug at home before smuggling it into the United States. Indeed, 97 percent of the methamphetamine seized by Customs and Border Protection (CBP) occurs along the U.S.-Mexican border, according to the Drug Enforcement Administration's 2018 National Drug Threat Assessment. So what exactly is driving this record-setting production of methamphetamine? For me, two main factors are responsible: economics and cartel dynamics. Ultimately, a combination of high-quality drugs, record-low prices and the massive competition among ever-splintering cartels is flooding the hungry U.S. market...