Mexico–United States border in the context of "Las Cruces, New Mexico"

Northern America is the northernmost subregion of North America, as well as the northernmost region in the Americas. The boundaries may be drawn significantly differently depending on the source of the definition. In one definition, it lies directly north of Middle America. Northern America's land frontier with the rest of North America then coincides with the Mexico–United States border. Geopolitically, according to the United Nations' scheme of geographical regions and subregions, Northern America consists of Bermuda, Canada, Greenland, Saint Pierre and Miquelon and the United States (the contiguous United States and Alaska only, excluding Hawaii, Navassa Island, Puerto Rico, the United States Virgin Islands, and other minor U.S. Pacific territories).

The Egypt–Israel barrier or Egypt–Israel border fence (Hebrew: שְׁעוֹן הַחוֹל, romanized: Sheʽon HaḤol, lit. 'sand clock') refers to a separation barrier built by Israel along its border with Egypt. Initial construction on the barrier began on 22 November 2010, and its original purpose as a common fence was to curb the large influx of illegal migrants from African countries into Israel. However, in the wake of the Egyptian Crisis after the 2011 Revolution, Israel's southwestern border with Egypt experienced an increase in militant jihadist activity with the outbreak of the Sinai insurgency. In response, Israel upgraded the steel barrier—called Project Hourglass by the Israel Defense Forces (IDF)—to include cameras, radars, and motion detectors. In January 2013, construction on the barrier's main section was completed; the final section was completed in December 2013.

A number of countries, including the United States and India, have sent delegations to Israel to observe its border-controlling capabilities and the various technologies used by the IDF to secure Israel's boundaries against the Arab states. Some of these countries have expressed an interest in implementing Israeli strategies and technologies with their own border fences; the Trump administration cited Israel's border strategies as inspiration for the barrier built by the United States along its border with Mexico, while Indian officials have discussed the implementation of an "Israel-type model" for the barrier built by India along its border with Pakistan.

Throughout U.S. history, the country experienced successive waves of immigration, particularly from Europe and later on from Asia and from Latin America. Colonial-era immigrants often repaid the cost of transoceanic transportation by becoming indentured servants where the employer paid the ship's captain. In the late 19th century, immigration from China and Japan was restricted. In the 1920s, restrictive immigration quotas were imposed but political refugees had special status. Numerical restrictions ended in 1965. In recent years, the largest numbers of immigrants to the United States have come from Asia and Central America (see Central American crisis).

Attitudes towards new immigrants have fluctuated from favorable to hostile since the 1790s. Recent debates have focused on the southern border (see Illegal immigration to the United States and Mexico–United States border wall) and the status of "dreamers", people who illegally migrated with their families when they were children and have lived in the U.S. for almost their entire lives (see Deferred Action for Childhood Arrivals).

Texas (/ˈtɛksəs/ TEK-səss) is the most populous state in the South Central region of the United States. It borders Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the west, and an international border with the Mexican states of Chihuahua, Coahuila, Nuevo León, and Tamaulipas to the south and southwest. Texas has a coastline on the Gulf of Mexico to the southeast. Covering 268,596 square miles (695,660 km) and with over 31 million residents as of 2024, it is the second-largest U.S. state by both area and population. Texas is nicknamed the "Lone Star State" for the single star on its flag, symbolic of its former status as an independent country, the Republic of Texas.

Spain was the first European country to claim and control Texas. Following a short-lived colony controlled by France, Mexico controlled the land until 1836 when Texas won its independence, becoming the Republic of Texas. In 1845, Texas joined the United States of America as the 28th state. The state's annexation set off a chain of events that led to the Mexican–American War in 1846. Following victory by the United States, Texas remained a slave state until the American Civil War, when it declared its secession from the Union in early 1861 before officially joining the Confederate States on March 2. After the Civil War and the restoration of its representation in the federal government, Texas entered a long period of economic stagnation.

Southern California (commonly shortened to SoCal) is a geographic and cultural region that generally comprises the southern portion of the U.S. state of California. Its densely populated coastal region includes Greater Los Angeles (the second-most populous urban agglomeration in the United States) and San Diego County (the second-most populous county in California). The region generally contains ten of California's 58 counties: Los Angeles, San Diego, Orange, Riverside, San Bernardino, Kern, Ventura, Santa Barbara, San Luis Obispo, and Imperial counties.

Although geographically smaller than Northern California in land area, Southern California has a higher population, with 23.76 million residents as of the 2020 census. The sparsely populated desert region of California occupies a significant portion of the area: the Colorado Desert, along with the Colorado River, is located on Southern California's eastern border with Arizona, and the Mojave Desert shares a border with Nevada to the northeast. Southern California's southern border with Baja California is part of the Mexico–United States border.

California (/ˌkælɪˈfɔːrniə/) is a state in the Western United States that lies on the Pacific Coast. It borders Oregon to the north, Nevada and Arizona to the east, and shares an international border with the Mexican state of Baja California to the south. With almost 40 million residents across an area of 163,696 square miles (423,970 km), it is the largest state by population, third-largest state by area and the largest state economy in the U.S., with a GDP of approximately $4.1 trillion.

Prior to European colonization, California was one of the most culturally and linguistically diverse areas in pre-Columbian North America. European exploration in the 16th and 17th centuries led to the colonization by the Spanish Empire. The area became a part of Mexico in 1821, as a result of its successful war for independence. Following the U.S. conquest of California, part of the Mexican-American War, California was ceded to the United States in 1848. The California gold rush started in 1848 and led to social and demographic changes, including the California genocide. It organized itself and was admitted as the 31st state in 1850 as a free state, following the Compromise of 1850.

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 649 miles (1,044 km) of barriers in place. A total of 438 miles (705 km) of new primary barriers were built during Donald Trump's first presidency, dubbed the "Trump wall", though Trump had repeatedly promised a "giant wall" spanning the entire border and that Mexico would "pay for the wall," neither of which were done. The national border's length is 1,954 miles (3,145 km), of which 1,255 miles (2,020 km) is the Rio Grande and 699 miles (1,125 km) is on land.

The Southwestern United States, also known as the American Southwest or simply the Southwest, is a geographic and cultural region of the United States that includes Arizona and New Mexico, along with adjacent portions of California, Colorado, Nevada, Oklahoma, Texas, and Utah. The largest cities by metropolitan area are Phoenix, Las Vegas, El Paso, Albuquerque, and Tucson. Before 1848, in the historical region of Santa Fe de Nuevo México as well as parts of Alta California and Coahuila y Tejas, settlement was almost non-existent outside of New Mexico's pueblos and Spanish or Mexican municipalities. Much of the area had been a part of New Spain and Mexico until the United States acquired the area through the Treaty of Guadalupe Hidalgo in 1848 and the smaller Gadsden Purchase in 1854.

While the region's boundaries are not officially defined, there have been attempts to do so. One such definition is from the Mojave Desert in California in the west (117° west longitude) to Carlsbad, New Mexico, in the east (104° west longitude); another says that it extends from the Mexico–United States border in the south to the southern areas of Colorado, Utah, and Nevada in the north (39° north latitude). In another definition, the core Southwestern U.S. includes only the states of Arizona and New Mexico; others focus on the land within the old Spanish and Mexican borders of the Nuevo México Province or the later American New Mexico Territory.