The most recent revision in the Texas-Mexico border was in 1964 when the U.S. returned 600 acres in South El Paso, know as the Chamizal, back to Mexico.
The following time line and map are helpful to those interested in understanding the history of the current U.S.-Mexico border:
1519-1521: Hernan Cortes invades and conquers the natives of central Mexico.
1535: Spain claims Mexico as colony and sets up a colonial government
1819: In the Adams-Onis Treaty, also know as the Transcontinental Treaty, the U.S. agrees to pay up to $5 Million to Spain in an agreement that defines a border between Spanish land and the Louisiana Territory. Spain retains possession of Texas west of the Sabine River as well as lands then known as the California and New Mexico Territories.
1821-1824: Mexico becomes independent from Spain. Stephen F. Austin gains approval to start a colony in Texas.
1836: Texas wins war of independence from Mexico.
1845: Texas becomes a state.
1846-1848: Mexican-American War ends. In the Treaty of Guadalupe-Hidalgo land is seceded by Mexico which redefines the border and splits El Paso del Norte, making the north bank a part of Texas. Later the south bank is named Ciudad Juarez and the north bank is named El Paso.
1853: The Gadsden Purchase Treaty is signed and United States pays Mexico $15 Million for 30,000 square miles south of The Gila River. The Mesilla Valley of New Mexico is thus linked to California for the purpose of constructing a railroad to link the Atlantic and Pacific coasts together.
1862-1900: Mexico is pressured by European countries for payment of loans and Benito Juarez looses control Mexico. France installs Archduke Maximilian as emperor, and then in 1867 withdraws support allowing Juarez to regain control. Mining and rail construction in the U.S. provides jobs for many Mexicans.
1904: Border patrol groups are formed to stop Asian workers from entering The United States through Mexico.
1910: The Mexican Revolution begins and thousands flee across the border for safety.
1916: Poncho Villa raids the New Mexican town of Columbus and is pursued into Mexico unsuccessfully by 10,000 American troops lead by General John J. Pershing.
1917: The U.S. enters WWI after the Germans approaches Mexico with a proposal to form an armed alliance. Pershing and his troops are withdrawn from Mexico and sent to the war in Europe.
1964: The last geographical change in the border, to date, occurs on September 24 as President Lyndon B. Johnson returns the Chamizal to Mexico. Due to a shift in the natural flow of the Rio Grande, Mexico had disputed the U.S. occupation of 600 acres parcel of land on the El Paso-Ciudad Juarez Border for decades.
