A lawmaker in Mexico this week scaled a massive fence on the United States’ southern border to protest what he called President Donald Trump’s “absurd and unnecessary” pledge to build a wall.

“I climbed the wall,” Braulio Guerra, a congressman from the governing Institutional Revolutionary Party (PRI), posted on Twitter March 1. Photos show Guerra and two others on top of a section of a wall built along the border between Baja California and San Diego County.

Trump has famously called for building a wall along the U.S. border with Mexico, which stretches over 1,950 miles — and making Mexico pay for it, a suggestion laughed off by Mexican politicians and profanely denounced by former President Vincente Fox.

Guerra, hailing from the central Mexican state of Querétaro, said the wall he climbed — built in 1996, according to The San Diego Union-Tribune, and up to 18 feet high — shows Trump’s plans for building his way to keeping people out are destined to fail.

“This is proof that the wall will not stop the flow of migration,” Guerra declared in a March 1 statement.

Despite the border wall in San Diego County, nearly 32,000 undocumented immigrants were apprehended there by U.S. Border Patrol in fiscal year 2016. That’s up compared to recent years, but far below what it was in 2000, when over 151,000 people were caught by Border Patrol agents in the county.

Those numbers suggest the flow of immigrants coming through Mexico has more to do with the U.S. economy than any structures on the southern border. In 2000, that economy was on the tail end of a boom; by 2008, the U.S. was hit by what’s now called the Great Recession — and apprehensions in San Diego County plummeted, falling by 42 percent between 2008 and 2010.

In the five years after the recession began, more Mexicans left the U.S. then came to it, according to an analysis by the Pew Research Center.

If Trump wants to reduce the number of undocumented immigrants coming into the country, then, statistics suggest he might be better off hurting the economy than building a wall.