Iowa has seen a significant drop in seizures of clandestine methamphetamine labs – from 120 to just 20 a month – just seven months after the state passed a law restricting the sale of cold medicines diverted to make methamphetamine. Having made inroads in curbing the domestic production of meth in their state, Iowa officials now have a new problem to contend with: the influx of a more potent form of crystal methamphetamine flooding in from Mexico.

Sometimes called ice, crystal methamphetamine is by far more pure, and therefore can be even more highly addictive, than powdered home-cooked methamphetamine, a change that health officials say has led to greater risk of overdose.

In South Dakota, officials boast that their law passed in May and restricting pseudoephedrine, the active ingredient and most cold medicines used to make meth, has been faster than any other state's in reducing methamphetamine laboratories. Still, when Mr. Van Haaften, director of the Governor's Office of Drug Control Policy, surveyed the local police, 74 percent said that the law had not changed demand, and 61 percent said supply had remained steady or increased.

"You can't legislate away demand," said Betty Oldenkamp, secretary of human services in South Dakota, where the governor this month proposed tightening a law that last year restricted customers to two packs of pseudoephedrine per store. "The law enforcement aspects are tremendously important, but we also have to do something to address the demand.

Read Kate Zerneke’s assessment of this growing problem which appeared on the front page of The New York Times Potent Mexican Meth Floods In as States Curb Domestic Variety.