LAREDO, TEX. - Stashing cash in spare tires, engine transmissions and truckloads of baby diapers, couriers for Mexican drug cartels are moving tens of billions of dollars in profits south across the border each year, a river of dirty money that has overwhelmed U.S. and Mexican customs agents, The Washington Post reports.

Officials said stemming the flow of this cash is essential if Mexico and the United States hope to disrupt powerful transnational criminal organizations that are using their wealth to corrupt, terrorize and kill.

Despite unprecedented efforts to thwart the traffickers, U.S. and Mexican authorities are seizing no more than 1 percent of the cash, according to an analysis by The Washington Post based on figures provided by the two governments.

The major Mexican drug organizations write that off as the cost of doing business - losing a percentage far smaller than the fees for an ordinary wire transfer or ATM withdrawal, Mexican and U.S. law enforcement officials said.

The Obama administration recently proposed a $600 million surge in spending and personnel, including additional gamma-ray scanners and money-sniffing dogs, as part of an intensifying effort to capture the dollars going from U.S. drug consumers to Mexican mafias.

Read the entire story at washingtonpost.com