This article originally appeared in UC Berkeley CED News

Building a wall between the US-Mexico border was one of Donald Trump’s campaign promises, which has now led to an executive order mandating its construction. This, according to Professor Emeritus of City & Regional Planning Michael Dear, will not solve any security problems for the United States, but could make them worse.

Professor Dear was a recent guest on CNN’s Fareed Zakaria GPS to discuss the existing 650-mile wall on the US-Mexico border and how it has proved to be ineffective in stopping trans-border crossings. (A commercial will run before the video plays.)

Dear, who has studied the relationship between urban development, socio-economic aspects and the geographical border between the US and Mexico, argues in his 2013 book Why Walls Won’t Work (University of Oxford Press) that walls have historically had no impact on migration. “Instead of building more walls, we should create more connections. It would be important for our trade but also for our safety,” he said.

In an interview conducted by Italian news outlet RSI News, Dear further explained that the idea that the United States’s border is unregulated and open is a misconception: In fact, a wall already exists for much of the navigable parts of the border.

“It is important to know – especially for someone who does not live in the United States, a wall already exists and was built in the last 10 years along nearly a thousand kilometers of land frontier,” he explained. “The data collected and analyzed by me, however, suggests that this wall has had no impact or otherwise has been minimal.”

Dear also argues that the existing wall has actually made it easier for drug cartels and traffickers to transport goods across the border. “The narco-traffickers know which entry points are used and the type of checks carried out by the border police. They know exactly when to pass,” he said. “In a way, this barrier has regularized their criminal activities. The first wall, the existing one, has had no effect. And even this second wall will have no impact on human beings or drug trafficking. ”

“If we continue to deport a large number of people, and with the possible modification in trade treaties with Mexico, we threaten the border economy,” Dear concluded. “So we automatically create a market for criminal behavior. Not because the people want it, but out of desperation. And this brings new challenges to our security.”

Dear was also a guest on KCRW’s podcast, “DnA: Design & Architecture,” to discuss the ineffectiveness of the proposed wall. Listen to him speak with host Frances Anderton at the 19-minute mark here.