Rick Jervis

USA TODAY

BROWNSVILLE, Texas — Despite the 18-foot-tall iron security fence cutting through her family’s citrus farm, Bonnie Elbert still sees a relentless flow of undocumented immigrants and smugglers carrying trash bags full of drugs sneaking into this southern tip of the USA.

Elbert considers herself politically conservative and wants lawmakers to do something about illegal immigration. But the proposal to build a wall between the U.S. and Mexico to make America safer — a cornerstone of Republican presidential candidate Donald Trump's campaign — is unrealistic, she said.

“The one we have doesn’t really work,” Elbert said as she drove recently through Loop Farms, more than 700 acres of orange and grapefruit orchards the family has tended since the 1920s. “What makes them think a new one will?”

Trump's proposal to build a 40-foot-high wall across the U.S. border with Mexico and make Mexico pay for it sparked a Twitter clash between the GOP candidate and Mexican President Enrique Peña Nieto.

Residents on the border have lived for years with a close facsimile: 650 miles of metal fencing and other barriers erected in 2009 and stretching, in sections, from this Texas border city to the California coast. The fence, created through the 2006 Secure Fence Act, is nearly continuous along the border with Arizona, New Mexico and California, due to long stretches of federal land along the border. But in Texas, the fence is chopped up into multiple sections because the state's border with Mexico is comprised mostly of private property, which is harder to acquire and build on.

Trump has said he needs to build only about 1,000 miles of wall along the nearly 2,000-mile border with Mexico, due to natural barriers. But the current fence sparked costly legal fights with property owners, disrupted communities that straddle the border and has proven largely ineffective in stemming the flow of undocumented immigrants, according to residents, community leaders and border patrol officials.

Whoever pays for it, a newer, bigger wall would waste more money and be just as futile in preventing illegal crossings, Brownsville Mayor Tony Martinez said.

“It’s gibberish,” Martinez said. “It doesn’t prevent people from coming in or drugs from coming in. It’s not a deterrent and it’s not effective.”

He noted that Mexican drug lord Joaquín Guzmán, known as El Chapo, tunneled his way out of prison last year before being recaptured by Mexican marines. “We should learn from El Chapo,” he said. “They could always build tunnels.”

Days after the fence went up along the border near McAllen, border agents there realized the smugglers’ answer to the barrier: ladders.

Agents began collecting the 19-foot ladders — some wooden and homemade, others construction-grade aluminum — propped up against the 18-foot fence, said Chris Cabrera, a McAllen-based border patrol agent and vice president of the local chapter of the National Border Patrol Council, the agents’ union.

So many ladders piled up in their station that supervisors told the agents to stop bringing them in, he said. Meanwhile, the flow of immigrants and drugs continued unabated. Apprehensions in the Rio Grande Valley sector of the Border Patrol, which sees the largest number of crossings in the USA, has more than doubled from 60,989 in fiscal year 2009 to 147,257 last fiscal year, according to Border Patrol statistics.

The Border Patrol union has endorsed Trump because of his focus on border security and immigration reform, Cabrera said. But the concept of building a bigger wall without other measures, such as increased manpower and technology, is ill-informed, he said.

“If you’re in the business of selling ladders, it’s a good idea,” Cabrera said. “If you build a bigger wall, they’re going to come with bigger ladders.” He added: “If they’re thinking of putting up a wall as a be-all, end-all ... they’re looking in the wrong place.”

The security fence project also ran into a litany of private property lawsuits and environmental opposition that ran up costs and led to delays, said Denise Gilman, director of the Immigration Clinic at the University of Texas-Austin School of Law, who has studied the fence’s impact on the border. Most of the land along the Texas border is privately owned, making it much harder for the federal government to acquire and build on, she said.

After long legal challenges from property owners, federal officials built the fence in sections along the winding Texas border, bypassing some land owned by richer and politically connected owners and building through poorer neighborhoods, she said. A new wall will face similar challenges.

“I was frustrated to see the lessons from the last experience had not been learned effectively,” Gilman said. “It’s important for the public to understand that it’s not going to be possible to build a wall along the entire border.”

The current wall snakes through the Rio Grande Valley just south of Highway 281, at times cutting right through residents' lawns, and through old town Brownsville, where some of the city’s most historic buildings sit. Mark Clark bought his two-story brick building a decade ago and enjoyed the view of the Rio Grande he had from his second-story balcony. Today, the view is of a sprawling, rust-colored fence.

The fence has broken up the continuity and goodwill between Brownsville and Matamoros, its sister city across the river in Mexico, and created an eyesore that rankles most locals, Clark said. Across the river, Mexicans call it “El Berlin,” alluding to the 27-mile concrete wall that once divided East and West Berlin during the Cold War, Clark said.

And the migrants keep coming, he said.

“It’s just embarrassing,” Clark said. “This has been a psychological disaster and a colossal waste of money. When’s it going to end?”