Claudia Ibarra, 31, was taken into custody after U.S. Customs and Border Protection agents patted her down and "realized there was something down there," spokeswoman Teresa Small told The Associated Press on Friday.
A doctor removed from Ibarra a black package of drugs double-wrapped in condoms.
Ibarra, a U.S. citizen and resident of Yuma, Ariz., had attempted to cross the border at San Luis alone and on foot, according to authorities.
Per a tabulation of U.S. Border Patrol and U.S. Customs and Border Protection data by the Center for Investigative Reporting, more than 36,000 pounds of methamphetamine were seized by agents along the U.S.-Mexico border between 2005 and 2011.
Although that number pales in comparison to the amounts of marijuana and cocaine seized in the area during the same time period, the amount of meth reported appears to be increasing year over year.
A separate report by the AP notes that the spike in meth seizures "reflects a shift in production to Mexico after a U.S. crackdown on domestic labs."
According to the AP, drug mules - including children - have been discovered withcaches of meth hidden in many unlikely places.