In temperatures of 30 degrees Celsius (86 F), armed officers are supervising workers replacing vehicle barriers with bollards along the border between Santa Teresa in New Mexico USA, and San Jeronimo in Chihuahua Mexico - in line with tough new requirements from the US Department of Homeland Security.
Border Patrol spokesperson Ramiro Cordero said the new twenty mile stretch of bollards will not completely stop illegal crossing or trafficking, but is part of a new strategy to slow down movement and give agents more time to supervise the border.
"Anything that is put there can be climbed over. If we put up a 20-foot barrier, they'll get a 21-foot ladder. That's not really the idea. Our responsibility and our obligation as an agency is to guard our borders. If we are able to have something that makes it more difficult for people, vehicles and contraband to get to the United States illegally, all the better," he said.
US President Donald Trump has demanded Mexico reduce the flow of migrants as the two countries seek to renegotiate the North American Free Trade Agreement (NAFTA).
El Paso attorney Carlos Spector, who specialises in immigration law, said Trump's rhetoric is also part of a negotiation strategy.
"President Trump's style is to use threats as a means of negotiation-- and fear, and xenophobia and racism-- and, from the beginning of his campaign, the focus of the campaign has been anti-Mexican racism," he said.
After 14 months in office, Trump returns regularly to the anti-immigration theme that helped motivate conservative and Republican voters to win him the Presidency in 2016. Trump wants to have a strong impact on illegal immigration and would like to completely stop it, and has also sought to reduce legal immigration.
Trump's efforts have so far failed to produce a complete overhaul of America's immigration laws or full funding for his US-Mexican border wall in the Republican-led Congress.
US Customs and Border Protection say construction is expected to last over a year and cost $73.3 million dollars.