Mexico–United States border wall

thumb|Border fence near [[El Paso, Texas, in the mid 2000s]]

thumb|Border fence between [[San Diego's border patrol offices in California, U.S. (left) and Tijuana, Mexico (right)]]

A border wall has been built along portions of the Mexico–United States border in an attempt to reduce illegal immigration to the United States from Mexico. The barrier is not a continuous structure but a series of obstructions variously classified as "fences" or "walls".

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. In May 2011, the Department of Homeland Security (DHS) said it had of barriers in place. The national border's length is , of which is the Rio Grande and is on land.

President Joe Biden signed an executive order In October 2023, President Biden announced that he was restarting border wall construction on some parts of the border due to the surge of migrant crossings, constructing an additional of border wall.

In January 2025, re-elected president Donald Trump pledged to finish the border wall during his second term. In a May 2026 interview, Secretary of Homeland Security Markwayne Mullin stated that he expected the primary wall to be completed by April or June 2027, and the secondary wall to be completed before Trump left office. The border from the Gulf of Mexico to El Paso, Texas, follows the Rio Grande, a natural barrier. The barrier is on both urban and uninhabited sections of the border, where the most illegal crossings and drug trafficking have been observed in the past. These urban areas include San Diego, California, and El Paso, Texas. The fencing includes a steel fence varying in height between that divides the border towns of Nogales, Arizona, in the U.S. and Nogales, Sonora, in Mexico.

97% of border apprehensions (foreign nationals caught in the U.S. illegally) by the Border Patrol in 2010 occurred at the southwest border. The number declined 61% from 1,189,000 in 2005 to 723,842 in 2008 to 463,000 in 2010. The decrease in apprehensions is the result of numerous factors, including changes in U.S. economic conditions and border enforcement efforts. Border apprehensions in 2010 were at their lowest level since 1972. Total apprehensions for 2017, 2018, and 2019 were 415,517, 521,090, and 977,509, respectively. And while the barrier is along the border with Mexico, 80% of those apprehended are not Mexican.

As a result of the barrier, the number of people trying to cross in areas that have no fence, such as the Sonoran Desert and the Baboquivari Mountains in Arizona, has increased. Such immigrants must cross 50 miles (80 km) of inhospitable terrain to reach the first road, which is in the Tohono Oʼodham Indian Reservation.

Geography

The Mexico–U.S. border stretches from the Pacific Ocean in the west to the Gulf of Mexico in the east. Border states include the Mexican states of Baja California, Sonora, Chihuahua, Coahuila, Nuevo León, and Tamaulipas and the U.S. states of California, Arizona, New Mexico, and Texas.

{| class="wikitable sortable"

! U.S. state !! Border length !! Mexican states

| |California|| || Baja California

| |Arizona|| || Baja California, Sonora

| |New Mexico|| || Sonora, Chihuahua

| |Texas|| || Chihuahua, Coahuila, Nuevo León, Tamaulipas

| |Total|| || –

History

thumb|upright|Two men scale the border fence into Mexico near [[Douglas, Arizona, in 2009|alt=Two men scale the border fence into Mexico near Douglas, Arizona, in 2009]]

Origins

Territorial exchanges in the Mexican–American War (1846–1848) and the Gadsden Purchase (1853) largely established the current U.S.–Mexico border. Until the early 20th century, the border was open and largely unpatrolled, with only a few "mounted guards" patrolling its length. 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 first international bridge was the Brownsville & Matamoros International Bridge, built in 1910. The first barrier built by the U.S. (a barbed-wire fence to prevent the movement of cattle across the border) was built in Ambos Nogales between 1909 and 1911, The first barrier built by Mexico was likely a -tall wire fence built in 1918 explicitly for the purpose of directing the flow of people, also in Ambos Nogales. Barriers were extended in the following decades and became a common feature in border towns by the 1920s. In the 1940s, the U.S. Immigration and Naturalization Service built chain-link barriers along the border.

The U.S. Congress approved a $4.3 million request by Immigration and Naturalization Service, in 1978, to build a fence along the border to replace an existing fence near San Ysidro, California, and El Paso, Texas, and then build an additional of new fence. who was the first president to propose building a border fence. 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. 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.

U.S. president George H. W. Bush approved the initial 14 miles (22.5 km) of fencing along the San Diego–Tijuana border. In 1993, President Bill Clinton oversaw initial border fence construction which was completed by the end of the year. Starting in 1994, further barriers were built under Clinton's presidency as part of three larger operations to taper transportation of illegal drugs manufactured in Latin America and immigration: Operation Gatekeeper in California, Operation Hold-the-Line in Texas, and Operation Safeguard in Arizona. Clinton signed the Illegal Immigration Reform and Immigrant Responsibility Act of 1996, which authorized further barriers and the reinforcement of the initial border fence. The majority of the border barriers built in the 1990s were made out of leftover helicopter landing mats from the Vietnam War. In 2005, the border-located Laredo Community College obtained a fence built by the United States Marine Corps. The structure led to a reported decline in border crossings onto the campus. U.S. representative Duncan Hunter of California proposed a plan on November 3, 2005, calling for the construction of a reinforced fence along the entire United States–Mexico border. This would also have included a border zone on the U.S. side. On December 15, 2005, Congressman Hunter's amendment to the Border Protection, Anti-terrorism, and Illegal Immigration Control Act of 2005 (H.R. 4437) passed in the House, but the bill did not pass the Senate. This plan called for mandatory fencing along of the -long border. On May 17, 2006, the U.S. Senate proposed the Comprehensive Immigration Reform Act of 2006 (S. 2611), which would include of triple-layered fencing and a vehicle fence, but the bill died in committee.

Secure Fence Act of 2006

thumb|The [[United States Border Patrol in the Algodones Dunes, California]]

thumb|A section of the barrier, made out of steel slats, ending in the Pacific Ocean in [[San Diego–Tijuana]]

thumb|[[Douglas, Arizona, 2009]]

thumb|The border fence between El Paso and Juarez has an elaborate gate structure to allow floodwaters to pass under. The gates prevent people from being able to cross under and can be raised for floodwaters carrying debris. Beyond the fence is a canal and levee before the Rio Grande.

thumb|Aerial view of [[El Paso, Texas, (top and left) and Ciudad Juárez, Chihuahua, (bottom and right). The brightly lit border can clearly be seen as it divides the two cities at night. The dark section at left is where the border crosses Mount Cristo Rey, an unfenced rugged area.|alt=Aerial view of El Paso, Texas, and Ciudad Juárez, Chihuahua; the brightly lighted border can clearly be seen as it divides the two cities at night.]]

The Secure Fence Act of 2006, signed into law on October 26, 2006, by President George W. Bush authorized and partially funded the potential construction of of physical fence/barriers along the Mexican border. The bill passed with supermajorities in both chambers. 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.

The government of Mexico and ministers of several Latin American countries condemned the plans. Governor of Texas Rick Perry expressed his opposition, saying that the border should be more open and should support safe and legal migration with the use of technology. The barrier expansion was opposed by a unanimous vote by the Laredo, Texas, City Council. Laredo mayor Raul G. Salinas said that the bill would devastate Laredo. He stated, "These are people that are sustaining our economy by 40%, and I am gonna close the door on them and put [up] a wall? You don't do that. It's like a slap in the face." He hoped that Congress would revise the bill to better reflect the realities of life on the border.

Secretary Chertoff exercised his waiver authority on April 1, 2008, to "waive in their entirety" the Endangered Species Act, the Migratory Bird Treaty Act, the National Environmental Policy Act, the Coastal Zone Management Act, the Clean Water Act, the Clean Air Act, and the National Historic Preservation Act to extend triple fencing through the Tijuana River National Estuarine Research Reserve near San Diego.

By January 2009, U.S. Customs and Border Protection (CBP) 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. On January 16, 2009, DHS announced it was pledging an additional $50 million for that purpose, and signed an agreement with the U.S. Department of the Interior for use of the additional funding. In January 2009, U.S. Customs and Border Protection reported that it had more than of barriers in place.

Obama administration (2009–2017)

On March 16, 2010, DHS announced that there would be a halt to expanding the virtual fence beyond two pilot projects in Arizona. Contractor Boeing Corporation had numerous delays and cost overruns. Boeing had initially used police-dispatching software that was unable to process all of the information coming from the border. The $50 million of remaining funding would be used for mobile surveillance devices, sensors, and radios to patrol and protect the border. At the time, DHS had spent $3.4 billion on border fences and had built of fences and barriers as part of the Secure Border Initiative. They'll never be satisfied. And I understand that. That's politics.</blockquote>

The Republican Party's 2012 platform stated that "The double-layered fencing on the border that was enacted by Congress in 2006, but never completed, must finally be built." The Secure Fence Act's costs were estimated at $6 billion, more than the Customs and Border Protection's entire annual discretionary budget of $5.6 billion. The Washington Office on Latin America noted in 2013 that the cost of complying with the Secure Fence Act's mandate was the reason that it had not been completely fulfilled.

A 2016 report by the Government Accountability Office confirmed that the government had completed the fence by 2015. A 2017 report noted that "In addition to the of primary fencing, [Customs and Border Protection] has also deployed additional layers of pedestrian fencing behind the primary border fencing, including of secondary fencing and of tertiary fencing."

First Trump administration (2017–2021)

thumb|left|President [[Donald Trump signing Executive Order 13767]]

The concept for the proposed expansion of the border wall was developed in 2014 by Donald Trump's 2015–2016 presidential campaign advisers Sam Nunberg and Roger Stone as a talking point Trump could use to tie his business experience as a builder and developer to his immigration policy proposals. The idea for the expansion of "the Wall", as Nunberg and Stone called it, was first aired publicly in January 2015 at the Iowa Freedom Summit hosted by Citizens United and Steve King. Mexican president Enrique Peña Nieto maintained that his country would not pay for the wall.

On January 25, 2017, the Trump administration signed Executive Order 13767, which formally directed the U.S. government to begin attempting to construct a border wall using existing federal funding, although construction did not begin at this time because a formal budget had not been developed. In March 2017, U.S. Customs and Border Protection (CBP) began accepting prototype ideas for a U.S.–Mexico border wall from companies and said it would issue a request for proposals by March 24.

In 2013, a Bloomberg Government analysis estimated that it would cost up to $28 billion (~$ in ) annually to seal the border. While campaigning for the presidency in early 2016, Trump claimed it would be a one-time cost of only $8 billion, while Republican House speaker Paul Ryan and Senate majority leader Mitch McConnell said $15 billion, and the Trump administration's own early estimates ranged up to $25 billion. The Department of Homeland Security's internal estimate in early 2017, shortly after Trump took office, was that his proposed border wall would cost $21.6 billion and take 3.5 years to build.

In September 2017, the U.S. government announced the start of construction of eight prototype barriers made from concrete and other materials. On June 3, 2018, the San Diego section of wall construction began. On October 26, a stretch of 30-foot steel bollards in Calexico, California, was commemorated as the first section of Trump's wall, although media coverage heavily debated whether it should be considered a "wall" or a "fence". Trump scheduled a visit to this section in April 2019.

Trump's campaign promise has faced a host of legal and logistical challenges since. In March 2018, the Trump administration secured $1.6 billion from Congress for projects at the border for existing designs of approximately of new and replacement walls. 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.

On May 24, 2019, federal judge Haywood Gilliam in the Northern District of California granted a preliminary injunction preventing the Trump administration from redirecting funds under the national emergency declaration issued earlier in the year to fund a planned wall along the border with Mexico. The injunction applies specifically to money the administration intended to allocate from other agencies and limits wall construction projects in El Paso and Yuma. 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). The decision was upheld five days later by a majority in the Ninth Circuit Appeals Court but was overturned by the U.S. Supreme Court on July 26. On September 3, Secretary of Defense Mark Esper authorized the use of $3.6 billion in military construction funding for of the barrier. The House and Senate have twice voted to terminate Trump's emergency declaration, but the president vetoed both resolutions. In October, a lawsuit filed in El Paso County produced a ruling that the emergency declaration was unlawful, as it fails to meet the National Emergencies Act's definition of an emergency. On December 10, a federal judge in the case blocked the use of the funding, but on January 8, 2020, a federal appeals court granted a stay of the ruling, freeing $3.6 billion for the wall.

thumb|upright=1.2|President [[Donald Trump with a section of the border wall near Yuma, Arizona, June 2020]]

, the Trump administration's barrier construction had been limited to replacing sections that needed repair or outdated, with of replacement wall built in the Southwest since 2017. As of September 12, 2019, the Trump administration plans for "Between 450 and 500 miles (724–806 kilometers) of fencing along the nearly 2,000-mile (3,218-kilometer) border by the end of 2020" with an estimated total cost of $18.4 billion. Privately owned land adjacent to the border would have to be acquired by the U.S. government to be built upon.

On June 23, 2020, Trump visited Yuma, Arizona, for a campaign rally commemorating the completion of of the wall. U.S. Customs and Border Protection confirmed that almost all of this was replacement fencing. By the end of Trump's term on January 21, 2021, had been built at last report by CBP on January 5, much of it replacing outdated or dilapidated existing barriers.

Contractors and independent efforts

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. 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. The company maintained that it could erect of the barrier for $3.3 billion and be able to complete it in 13 months. 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 away. The proposed barrier would be constructed with near Yuma and near Tucson, Arizona, near El Paso, Texas, and near El Centro, California—reportedly costing $12.5 million per mile ($7.8 million per kilometer). U.S. senator Kevin Cramer was also there, promoting Fisher Industries, which demonstrated the construction of a fence in Coolidge.

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. Over the 2019 Memorial Day weekend, the organization constructed a to "weathered steel" bollard fence near El Paso on private land adjoining the U.S.–Mexico border using $6–8 million of the donated funds. Kolfage's organization says it has plans to construct further barriers on private lands adjoining the border in Texas and California. 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. On January 9, 2020, a federal judge lifted an injunction, allowing a construction firm to move forward with the project along the Rio Grande. This ended a month long court battle with both the Federal Government and the National Butterfly Center which both tried to block construction efforts. By August 2020, the portions constructed by the organization were already in serious danger of collapsing due to erosion, and the acting U.S. attorney for the Southern District of New York unsealed an indictment charging four people, including Bannon, with a scheme to defraud hundreds of thousands of donors by illegally taking funds intended to finance construction for personal use. An unpublished memo from the U.S. Customs and Border Protection leaked in March 2022 revealed that the wall had been breached more than 3,200 times from October 2018 to September 2021. Nonetheless, CBP officials say the bollard fencing remains a valuable border security tool when combined with surveillance technology and sufficient personnel.

Outcome

As of December 2020, the total funding given for new fencing was about $15 billion (~$ in ), a third of which had been given by Congress while Trump had ordered the rest taken from the military budget. This funding was intended to build new fencing over , at a cost of about $20 million per mile ($12.5 million per kilometer); this would cover a little more than half the approximately that had no fencing when Trump took office.

A March 2021 review of the Trump work on the wall found only of new barriers where none had previously existed. While Trump had described the new wall as "virtually impenetrable", it was found that smugglers had repeatedly sawed through the wall with cheap power tools. Also, new dirt roads that had been used to access the wall construction served as new access roads for smugglers.

Biden administration (2021–2025)

President Joe Biden signed an executive order on his first day of office, January 20, 2021, ordering a "pause" in all construction of the wall no later than January 27. The government was given two months to plan how to spend the funds elsewhere and determine how much it would cost to terminate the contracts. There were no plans to tear down parts of the wall that had been built. The deployment of 3,000 National Guard troops along the border continued. Furthermore, the Biden administration continued to seize land for construction of the border wall. By December 2021, many contracts had been cancelled, including one requiring the possession of the land of a family represented by the Texas Civil Rights Project.

In June 2021, Texas governor Greg Abbott announced plans to build a border wall in his state, saying that the state would provide $250 million and that direct donations from the public would be solicited. On June 29, the Republican Study Committee organized a group of two dozen Republican House members to visit a gap in the border where Central Americans were crossing into the country. Representative Mary Miller stated that "obviously our president has advertised this and facilitated this invasion". Rep. Jim Banks praised the effectiveness of Trump's wall and said that because of the halted construction, "thousands of migrants [pass] through this area regularly... 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 stated, "They're basically treating people like Amazon products. ... There is no care that that is a human being, someone who has a soul, someone who has unalienable rights that predate any government." 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. To expedite production, the Biden administration would waive more than two dozen laws that "protect air, water and endangered species" such as the Clean Air Act, the Endangered Species Act and the National Historic Preservation Act. The administration claimed that the money for the wall construction was "allocated during Trump's term in 2019." In 2021, the congress controlled by the Democratic Party ignored Biden's request to rescind the funds. The decision was praised by former president Donald Trump and criticized by Mexican president Andres Manuel Lopez Obrador as "a step backwards" and Jonathan Blazer, director of border strategies for the American Civil Liberties Union as "doubling down on the failed policies of the past."

Binational River Park

In 2021, in collaboration with the United States and Mexican ambassadors, as well as businessmen, a binational park was proposed along the Rio Grande between the border towns of Laredo, Texas and Nuevo Laredo, Mexico. Supported by the No Border Wall Coalition, the park aims to create a shared recreational space instead of a border wall. Earthjustice estimated that the decision not to build a border wall in Laredo saved of river from destruction and over $1 billion in taxpayer dollars.

Arizona container wall

thumb|The Arizona container wall.

In August 2022, Arizona governor Doug Ducey ordered the erection of a makeshift wall of shipping containers on the border with Mexico in Cochise County, Arizona. The construction began in the Coronado National Forest without authorization from the U.S. Forest Service, which operates the land. Ecologists at the Center for Biological Diversity argue that the construction, which imperils at-risk species including the ocelot and jaguar, violates the Endangered Species Act of 1973 and have sued to halt its construction. Governor-elect Katie Hobbs stated that she would remove the containers after taking office, and the U.S. Justice Department sued the state to remove the containers and "compensate the [U.S.] for any actions it needs to take to undo Arizona's actions". Deconstruction of the container wall had begun by January 2023.

Second Trump administration (2025–present)

In January 2025, re-elected president Donald Trump pledged to finish the wall during his second term. In January 2025, he declared a national emergency to direct the departments of State and Defense to resume construction of the wall.

President Trump initially utilized residual FY 2021 funds that were not spent by the Biden administration to continue work on the border wall. On March 15, 2025, U.S. Customs and Border Protection (CBP) announced that it had awarded the first border wall contract of President Trump’s second term to construct approximately seven miles of new border wall in Hidalgo County, Texas, within the U.S. Border Patrol’s (USBP) Rio Grande Valley (RGV) Sector. This contract was funded with CBP’s Fiscal Year 2021 funds. On June 18, 2025, U.S. Customs and Border Protection awarded its second contract for border wall construction for approximately 27 miles of new border wall in Santa Cruz County, Arizona located within the U.S. Border Patrol’s Tucson Sector. This contract was funded with CBP’s fiscal year 2021 funds. Additional contracts followed which used these previously appropriated funds.

On July 3, 2025, the Republican-controlled Congress passed the One Big Beautiful Bill Act which includes $46.5 billion to complete construction of the wall on the United States–Mexico border, along with:

$17.3 billion to support state and local law enforcement with border enforcement.
$10 billion to reimburse the Department of Homeland Security for costs related to border security.
$7.8 billion for hiring Border Patrol agents and vehicles, to hire 3,000 new agents.

Border wall is being constructed in the areas of Tucson, Arizona, and San Diego, California area. The administration contracted with Anduril, General Dynamics, and Elbit to install autonomous surveillance towers along the border. Over $2.5 billion in funding was awarded to construct floating barriers in the Rio Grande. In June 2025, Department of Homeland Security permitted 36 miles of wall to be built across Arizona and New Mexico with additional wall barrier to be built following waivers of environmental regulations. As of mid-December 2025, United States Customs and Border Patrol was averaging two miles of wall installed per week, and it intended to increase this to 10 miles per week, according to CBP Chief Mike Banks. In December 2025, DHS signed a $609 million contract with Parsons to oversee border wall construction. The Department of Interior transferred 760 acres of public land near the border to the navy in December 2025 to establish a National Defense Area. In a May 2026 interview, Secretary of Homeland Security Markwayne Mullin stated that he expected the primary wall to be completed by April or June 2027, and the secondary wall to be completed before Trump left office.

Concerns and impacts

thumb|upright=2|This 2017 fence upgrade at [[Anapra was planned by the Obama administration.]]

thumb|Work on a higher replacement fence begins on a section of border fence near [[Calexico, California, United States, and Mexicali, Mexico, in 2018.]]

Effectiveness

Different sources draw different conclusions about the actual or likely effectiveness of the wall. Experts on the subject have said that aside from the human crossings, drugs, among other things, will still be making their way to the United States illegally. U.S. Customs and Border Protection has frequently called for more physical barriers on the Mexico–United States border, citing their efficacy. However, research at Texas A&M University and Texas Tech University indicated that the wall, and border walls in general, are unlikely to be effective at reducing illegal immigration or movement of contraband. By contrast, the American Economic Journal found that wall construction caused a 15–35% reduction in migration, varying with proximity to the barrier.

Critics of Trump's plan note that expanding the wall would not stop the routine misuse of legal ports of entry by people smuggling contraband, overstaying travel visas, using fraudulent documents, or stowing away. They also point out that in addition to the misuse of ports of entry, even a border-wide wall could be bypassed by tunneling, climbing, or by using boats or aircraft. Additionally, along some parts of the border, the existing rough terrain may be a greater deterrent than a wall.