The newspaper, which conducted a year-long investigation of arms smuggling into Mexico and is publishing the results in a series of articles, said Carter's Country, the operator of four gun stores in the metro Houston area, accounted for more than 115 firearms seized by Mexican police and soldiers.

"As an unprecedented number of American guns flows to the murderous drug cartels across the border, the identities of U.S. dealers that sell guns seized at Mexican crime scenes remain confidential under a law passed by Congress in 2003," the newspaper said.

Eight of the top gun dealers providing arms traced from Mexico are in Texas, three in Arizona and one in California, the Post said.

Two of the four Carter's Country stores in Houston and four gun shops in the Rio Grande Valley made the list.

Texas has 3,800 gun dealers, with 300 gun shops located in Houston alone.

Over the past four years, Mexican and U.S. authorities have traced more than 60,000 firearms used in crimes in Mexico to about 7,500 gun dealers along the border.

Investigators identified 185 firearms from Lone Wolf Trading Company in Glendale, Arizona, 165 from the Glick Twins gun shop in Texas, 130 from J&G Sales in Prescott, Arizona, and 120 from Denny's Pawn and Sporting Goods in McAllen, Texas.

"Drug cartels have aggressively turned to the United States because Mexico severely restricts gun ownership. Following gunrunning paths that have been in place for 50 years, firearms cross the border and end up in the hands of criminals as well as ordinary citizens seeking protection," the Post said.