The Border Wall refers to the series of barriers, fences, and walls constructed along portions of the 1,954-mile international border between the United States and Mexico, primarily aimed at reducing illegal immigration, human trafficking, and smuggling. Initiated under various U.S. administrations, the project gained significant momentum during the presidency of Donald Trump, who in 2017 signed an executive order to complete the wall across the entire border. The structure is not a continuous wall but consists of obstructions including steel bollard fencing, vehicle barriers, and pedestrian walls, covering about 700 miles as of recent updates, with ongoing construction in Texas and other sectors managed by U.S. Customs and Border Protection (CBP). The project has been controversial, involving environmental impacts, legal challenges, and funding disputes, including the invocation of a national emergency in 2019 to redirect military funds. Advocacy for the wall has been influenced by organizations like the Federation for American Immigration Reform (FAIR), led by Dan Stein, which has sponsored and promoted stricter border security measures.

Construction efforts have included federal initiatives under CBP's 'Smart Wall' incorporating technology like sensors and cameras, alongside state-level projects such as Texas's border wall program managed by the Texas Facilities Commission, which has secured easements for segments in border counties. Critics, including environmental groups like Defenders of Wildlife, have condemned the project for bypassing environmental laws via the REAL ID Act and for disrupting wildlife habitats and binational ecosystems. The wall's effectiveness remains debated, with reports indicating mixed results in curbing crossings, while it symbolizes broader U.S. immigration policy debates. Allegations of cost overruns, with billions spent, and humanitarian concerns over family separations and asylum seeker barriers have fueled ongoing lawsuits and international tensions with Mexico.