By Dan Frosch and Dudley Althaus

McAllen, Texas -- Some officials and residents in border states that have benefited from stronger ties with Mexico reacted with concern over the potentially negative impact building a wall could have on regional economies, while expressing support for enhanced security along the border.

Wednesday's executive order, coupled with President Donald Trump's vow to renegotiate the North American Free Trade Agreement, have made many who live along the border uneasy about the economic future of the borderlands.

"It sends the wrong message to a pivotal partner and friend," said Steve Ahlenius, president of the chamber of commerce in McAllen, a Texas city of 140,000, long a favorite shopping destination for Mexicans from the city of Monterrey.

Long stretches of the border here are already fenced off -- with tall and tightly spaced rust-colored steel beams protruding up from the scrub brush. Like other local business leaders, Mr. Ahlenius said he worried that the optics of a full-fledged effort by Mr. Trump to extend the wall would compel Mexicans to take their business elsewhere.

"We were hoping he would soften his position," said Pete Saenz, the mayor of Laredo, a city of 270,000 along the Mexican border that has thrived because of trade with Mexico. Mr. Saenz, elected as an independent, voted for Mr. Trump.

But he said he disagreed with him on this issue and feared it would impact Laredo's economy, enmeshed with Mexico's.

The population of Laredo has grown exponentially since the mid-1990s. According to state data, Laredo's customs district accounted for $284 billion in trade, more than double the amount it saw in 2002.

Others though, praised the president's actions. Texas Republicans in particular have called for tighter controls and greater enforcement, and said too much of the work on border protection has fallen on the state.

Governor Greg Abbott, a Republican, said through a spokeswoman that he was "pleased with the immediate action President Trump has taken to fulfill his promise to secure the border."

U.S. Congressman Roger Williams, a Republican from Austin, commended Mr. Trump for taking on the border issues during his first week in office, saying it was important that immigrants were funneled through legal ports of entry "not between them."

And some border residents said they supported the idea.

Butch Emery, 68, who grows cotton, sugar cane and grains on his riverfront land in the village of Relampago, about 20 miles downstream from McAllen, says he considers the wall necessary.

"I don't understand why everyone is so concerned," said Mr. Emery, adding he doesn't think a wall will impact the economy. "If people are legal they don't have any problem coming across to visit their family or friends or to go shopping."

"You people who don't live here don't have to put up with the trash and all," Mr. Emery said of the refuse and other damage left by migrants crossing his property on their way north.

After a lull, the southwestern border experienced a renewed surge of Central American migrants illegally crossing into the U.S. Federal statistics for the fiscal year ending Sept. 30 showed a 90% increase in detentions of women with children or minors from 2015.

Even some who support tighter border security said constructing a wall was impractical and unnecessary, because of existing fencing in some areas and natural barriers like the Rio Grande in others. And some here said that a more secure border could be achieved through a combinationof expanded fencing, more Border Patrol officers and virtual technology.

"Building a wall is the most expensive and least effective way to secure the border," said Congressman Will Hurd, a Texas Republican whose district includes over 800 miles of the border, in a statement. "A wall may be an effective tool in densely populated areas, but a variety of tools are needed between Brownsville, Texas and San Diego, California."

In Nuevo Progreso, on the Rio Grande across from the Texas town of Pharr, scores of American retirees clogged the sidewalks, stores and restaurants Wednesday. The town lives on the business of retirees from the U.S. heartland who spend the winter in far South Texas.

People come for dentistry and medical care, cheap prescription drugs, and to spend a few hours drinking beer or margaritas. Many seemed skeptical the wall would ever be built.

"It's not a very good idea," said Tom Lynch, an Army retiree fromMissouri. "Most people we know like the wall, but we'd rather have him spend the money on bridges and highways.

Texas' border cities in particular also worry about Mr. Trump's promise to renegotiate the North American Free Trade Agreement, which has benefited Texas.

The state is the nation's top exporter of goods, federal data show, and trade with Mexico is a critical cog in the economy here. From 1994, when Nafta took effect, to 2015, exports from the state to Mexico grew 236%, according to a recent report from the Federal Reserve Bank of Dallas.

Unemployment rates have also fallen dramatically in some Texas border cities since Nafta, federal data shows. In the McAllen area, for example, it dropped from roughly 22% in 1990 to 8% in 2016. Mexican customers make up 36 % of McAllen's retail sales, accounting for roughly $1.2 billion annually, according to the chamber of commerce.

Russ Jones, the chairman of the board of the Border Trade Alliance, which represents local governments and businesses on border issues, said he wanted to hear more about Mr. Trump's plan.

One the one hand, he said, a wall in certain areas, if fortified properly, and used in conjunction with other protective measures like drones could be "extremely effective," he said.

Conversely, Mr. Jones, whose family has lived on the Arizona border since the early 1900s and includes numerous relatives in Mexico, said there was a concern that further constricting the movement of legal residents on both sides who travel back and forth will be unpopular.

Mr. Jones, who heads up a customs brokerage firm with offices in California, Arizona and Texas, added, "If all we want to do is build this long wall so we can say 'I built this wall'...It didn't work for the Chinese, and it won't work for us."

Write to Dan Frosch at dan.frosch@wsj.com and Dudley Althaus at Dudley.Althaus@wsj.com(END) Dow Jones Newswires

January 25, 2017 20:21 ET (01:21 GMT)

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