EAGLE PASS, Texas (CNN) -- Every Sunday morning Luciano Valdez, his wife, Juanita, and daughter, Lisseth, pile into their minivan and head to Wal-Mart. Juanita looks at clothing and jewelry, while Luciano heads for the sporting goods department to check out fishing rods.

A family outing to Wal-Mart is a ritual played daily across the nation. But Valdez and his family's visit has an international dimension. The Valdezes live in Mexico but work and shop in the United States. They are part of the 230,000 residents of the twin cities of Piedras Negras, Mexico, and Eagle Pass, Texas, who divide their lives between two countries.

Founded simultaneously in the late 1890s, the cities share the Rio Grande, which also marks the border between Mexico and the United States. But they share much more.

"We have a river that divides us, but we don't think that way," says Urbano Santos, mayor of Piedras Negras. "We think the river unites us."

Valdez's family is Mexican. He was born in the United States by pure chance. "When she was about to give birth, my mother went shopping to Eagle Pass," he said. "She couldn't make it back home before she went into labor, so I was born in the United States."

His U.S. citizenship allows Valdez to work in the United States, something he says he prefers because wages are better than in Mexico.

But not everyone in Eagle Pass is working. The town has one of the highest unemployment rates in the United States, around 23 percent.

After the North American Free Trade Agreement (NAFTA) was implemented in 1994, many of the low-skill manufacturing jobs that supported the Eagle Pass economy were lost on both sides of the border. Many companies began operating in Mexico. Lower wages and the ease of movement between Mexico and the United States, made hundreds of companies move their operations south.

While Eagle Pass lost out on jobs after NAFTA, Mexico's opening up to free trade beyond North America ended up providing an economic bonanza for the Mexican border towns.

Shifting balance of power
Ten years ago towns such as Eagle Pass were the sources of jobs and money; the economic powerhouses today are cities such as Piedras Negras.

"Any manufacturing that existed on the border prior to NAFTA has basically died," said Frank Campney, who has lived and worked in the area since 1992.

Campney, who runs a high-tech, start-to-finish production plant in Piedras Negras, is seeing another shift taking place today. The manufacturing jobs that fled to Mexico in the mid-to-late 1990s are being lost to cheaper job markets in Asia and Central America.

Campney said he feels Mexican authorities have been proactive in their attitudes toward the changing economic dynamics on the U.S.-Mexico border. A better-educated work force and efforts by Mexico to establish itself as a bridge for trade between the United States and third countries have convinced U.S. manufacturers to head south.

"In the past, people just assumed those professional jobs had to be performed in the United States because that is where the skills were," Campney said. "What's happened is that Mexico has educated a young aggressive work force that is able to compete for jobs on a worldwide level.

" So towns such as Eagle Pass are scrambling to re-invent themselves. They are looking to capitalize on the cross-border interdependence by becoming the service sector for the booming economies across the Rio Grande.

Serving the work force
New hotels, golf courses and shopping centers are mushrooming in Eagle Pass. Construction on a new convention center is scheduled to begin in August. Local authorities say they recognize the need to re-educate the work force on the U.S. side of the river.

"I think the biggest need we have is the investment into the human capital when we talk about universities and about work force development," says Jose Aranda, mayor of Eagle Pass.

The dynamic is not limited to the Eagle Pass/Piedras Negras area. All along the border, the Mexican side is booming with new jobs and construction. U.S. cities such as El Paso and Laredo also are re-inventing themselves.

The interdependence that has dominated life on the border continues today, perhaps at a more urgent pace.

And that can only be good news for border residents such as Valdez, who have the options to live and work in two countries and two cultures, and to benefit from the economic change that is as dynamic as the border itself.

Watch Harris Whitbeck's video report Monday, June 4 on CNN.

Harris Whitbeck is CNN Mexico City bureau chief.