[2] Between the physical barriers, security is provided by a "virtual fence" of sensors, cameras, and other surveillance equipment used to dispatch United States Border Patrol agents to suspected migrant crossings.
On July 28, 2022, the Biden administration announced it would fill four wide gaps in Arizona near Yuma, an area with some of the busiest corridors for illegal crossings.
[19][20] But tensions between the U.S. and Mexico began to rise with the Mexican Revolution (1910) and World War I, which also increased concerns about weapons smuggling, refugees and cross-border espionage.
The proposed construction received press coverage after the company's George Norris, described the fence as a "razor-sharp wall", leading to negative responses in Mexico.
[23] The proposed wall, dubbed the "Tortilla Curtain" by critics,[26][27][28] was condemned by Mexican politicians such as then-president José López Portillo, and it was raised as an issue during President Jimmy Carter's state visit to Mexico in February 1979.
[35] The Secure Fence Act of 2006, signed into law on October 26, 2006, by President George W. Bush[36] authorized and partially funded the potential construction of 700 miles (1,100 km) of physical fence/barriers along the Mexican border.
[37][38] Secretary of Homeland Security Michael Chertoff announced that an eight-month test of the virtual fence he favored would precede any construction of a physical barrier.
[42] By January 2009, U.S. Customs and Border Protection and Homeland Security had spent $40 million on environmental analysis and mitigation measures aimed at blunting any possible adverse impact that the fence might have on the environment.
In March 2018, the Trump administration secured $1.6 billion from Congress for projects at the border for existing designs of approximately 100 miles (160 km) of new and replacement walls.
[57] From December 22, 2018, to January 25, 2019, the federal government was partially shut down because of Trump's declared intention to veto any spending bill that did not include $5 billion in funding for a border wall.
The injunction applies specifically to money the administration intended to allocate from other agencies and limits wall construction projects in El Paso and Yuma.
[59] On June 28, Gilliam blocked the reallocation of $2.5 billion of funding from the Department of Defense to the construction of segments of the border wall categorized as high priority by the Trump administration (spanning across Arizona, California and New Mexico).
[76] As of February 2019, contractors were preparing to construct $600 million worth of replacement barriers along the south Texas Rio Grande Valley section of the border wall, approved by Congress in March 2018.
[77][78] In mid-April 2019, former Kansas Secretary of State Kris Kobach visited Coolidge, Arizona, to observe a demonstration by North Dakota's Fisher Industries of how it would build a border fence.
Spin cameras positioned atop the fence would use facial-recognition technology, and underground fiber optic cables could detect and differentiate between human activity, vehicles, tunneling, and animals as distant as 40 feet (12 m) away.
[80] A private organization founded by military veteran Brian Kolfage called "We Build the Wall" raised over $20 million beginning in 2018, with President Trump's encouragement and with leadership from Kobach and Steve Bannon.
[81][82][83] On December 3, 2019, a Hidalgo County judge ordered the group to temporarily halt all construction because of its plans to build adjacent to the Rio Grande, which a lawyer for the National Butterfly Center argues would create a flooding risk.
Rep. Jim Banks (R-IN) praised the effectiveness of Trump's wall and said that because of the halted construction, "thousands of migrants [pass] through this area on a regular basis ... because there's an open door that allows them to do that".
In reference to wristbands on migrants used by Mexican cartels and smugglers to track them, Rep. Madison Cawthorn (R-NC) stated, "They're basically treating people like Amazon products.
Earthjustice estimated that the decision to not build a border wall in Laredo saved 71 miles (114 km) of river from destruction and over $1 billion in taxpayer dollars.
[117][118] On January 27, 2008, a Native American human rights delegation in the United States, which included Margo Tamez (Lipan Apache-Jumano Apache) and Teresa Leal (Opata-Mayo) reported the removal of the official International Boundary obelisks of 1848 by the U.S. Department of Homeland Security in the Las Mariposas, Sonora-Arizona sector of the Mexico–U.S.
[119][120] The obelisks were moved southward approximately 20 m (70 ft), onto the property of private landowners in Sonora, as part of the larger project of installing the 18-foot (5.5 m) steel barrier wall.
On August 20, 2008, the university sent out a request for bids for the construction of a 10-foot (3.0 m) high barrier that incorporates technology security for its segment of the border fence project.
[133] Between 1994 and 2007, there were around 5,000 migrant deaths along the Mexico–United States border, according to a document created by the Human Rights National Commission of Mexico, also signed by the American Civil Liberties Union.
Despite claims from then Homeland Security Chief Michael Chertoff that the department would minimize the construction's impact on the environment, critics in Arizona, New Mexico, and Texas, asserted that the fence endangered species and fragile ecosystems along the Rio Grande.
[141] About 100 species of plants and animals, many already endangered, are threatened by the wall, including the jaguar, ocelot, Sonoran pronghorn, Mexican wolf, a pygmy owl, the thick-billed parrot, and the Quino checkerspot butterfly.
According to Scott Egan of Rice University, a wall can create a population bottleneck, increase inbreeding, and cut off natural migration routes and range expansion.
[142][143] In 2008 a resolution "based on sound and accurate scientific knowledge" expressing opposition to the wall and the harmful impact on several rare, threatened, and endangered species, particularly endangered mammals such as the jaguar, ocelot, jaguarondi, and Sonoran pronghorn, was published by The Southwestern Association of Naturalists, an organization of 791 scientists specializing in the zoology, botany, and ecology of southwestern United States and Mexico.
[147] The U.S. Customs and Border Protection plans to build the wall using the Real ID Act to avoid the process of making environmental impact statements, a strategy devised by Chertoff during the Bush administration.
[149] In a January 2017 study conducted by the Pew Research Center, 39% of Americans identified construction of a U.S.–Mexico border wall as an "important goal for U.S. immigration policy".