LAREDO, Texas - If the shuttered factories that dot the Ohio landscape tell the story of NAFTA, so too do the miles of trucks carrying auto parts, fruit and tequila across the Mexican border through this booming port city in South Texas.

Democrats Barack Obama and Hillary Rodham Clinton roundly condemn NAFTA, the North American Free Trade Agreement, as they campaign across Ohio, which holds its primary Tuesday. But the candidates are relatively silent about the matter in Texas, another delegate-rich state holding a primary the same day — one that has seen an economic renaissance along its southern border since the agreement came into effect in 1994.

Signed into law by President Bill Clinton, NAFTA opened up trade between the U.S., Canada and Mexico by eliminating tariffs on most goods moved back and forth across those countries' borders. But the deal established no labor standards, encouraging manufacturers in Ohio and elsewhere to ship jobs to Mexico in order to produce goods more cheaply there.

NAFTA is highly unpopular in Ohio, where blue-collar workers are a pivotal force. But the agreement is widely praised in Laredo and other Texas border towns for bringing new life into a once poor and struggling region.

The border area — Laredo, the Rio Grand Valley — has been one of the areas most benefited by NAFTA. "There's no doubt about it," said Andres Rivas, an economics professor at Texas A&M International University who studies trade. "It's had a big, positive impact. I really don't see any down side."

President Bush, a former Texas governor, even stepped into the political fray this week to defend NAFTA.