In 2019, the U.S.-Mexico border topped the news, in part, because of the promise that President Donald Trump had made to build a wall along it. While Trump's border wall continues to be a popular topic today, the construction of barriers along the border is nothing new.

In his book “Border Land, Border Water: A History of Construction on the U.S.-Mexico Divide,” author C.J. Alvarez explores 150 years of border-barrier history. Alvarez is an assistant professor of Mexican-American and Latino studies at the University of Texas at Austin.

In his book, he looks at the history of the U.S.-Mexico border through the development of ports of entry, boundary markers, transportation networks, fences, barriers, surveillance infrastructure, dams and other river engineering projects. Some of these construction projects were complicated by the fact that in many places, the border itself is a river – the Rio Grande.