The border between the United States and Mexico, stretching almost 2,000 miles from California to Texas, was first established under the
1848 Treaty of Guadalupe Hidalgo (PDF). The border was further refined under the
Gadsden Treaty of 1853 (PDF), which reestablished the southern boundary of New Mexico and Arizona to enable the US to construct a railroad to the west coast along a southern route.
Both treaties established temporary joint commissions to survey, map and demarcate with landmarks the boundary between the US and Mexico. The
Convention of 1882 (PDF) established another temporary joint commission to resurvey the western land boundary between the Rio Grande and the Pacific Ocean, rebuild the old monuments and install additional monuments where necessary. During the late 1890s, US and Mexican commissioners resurveyed the borderline and increased the number of boundary monuments from 52 to 258. This survey started at the El Paso, Texas – Ciudad Juárez, Chihuahua border in 1891 and concluded at the San Diego, California – Tijuana, Baja California border in 1894. As border populations increased during the 1900’s, the commission installed 18 additional boundary monuments for a total of 276.
As the settlements grew along the boundary rivers of the Rio Grande and Colorado River, settlers began developing adjoining lands for agriculture. In the late 1800s, questions arose as to the location of the boundary and the jurisdiction of lands when the boundary rivers changed their course and transferred land from one side of the river to the other. As a result, the US and Mexico adopted rules to deal with such questions in the
Convention of 1884 (PDF).
The U.S. and Mexico established the International Boundary Commission (IBC) on March 1, 1889, as another temporary body to enforce the rules from the 1884 agreement. The IBC was extended indefinitely in 1900 and is considered the direct predecessor to the modern day IBWC. The 1884 Convention was modified by the
Banco Convention of March 20, 1905 (PDF) to retain the Rio Grande and the Colorado River as the boundary.
As border populations increased during the early to mid 1900's, the commission faced many new challenges. The US and Mexico used studies developed by the IBC as the basis for the first water distribution treaty between the two countries, the
Convention of March 1, 1906 (PDF), which allocated the waters of the Rio Grande from El Paso to Fort Quitman. This convention allotted to Mexico 60,000 acre-feet of water annually (an acre foot of water is equal to 325,851 gallons of water). To facilitate this water delivery, the US constructed the Elephant Butte Dam in its territory. The convention included a provision that in case of extraordinary drought or serious accident to the irrigation system in the U.S., the 60,000 acre-feet allotment can be reduced.
In the
Convention of February 1, 1933 (PDF), the two governments agreed to jointly construct, operate and maintain, through the IBC, the Rio Grande Rectification Project, which straightened and stabilized the 155-mile river boundary through the highly developed El Paso-Juárez Valley. The project further provided for the control of the river's floods through the valley.
The IBC was also instrumental in developing the second water distribution treaty between the United States and Mexico in 1944, which addressed utilization of the waters of the Colorado River and Rio Grande from Fort Quitman, Texas to the Gulf of Mexico. The
Water Treaty of February 3, 1944 (PDF) is one of the most important treaties affecting the boundary commission. With the signing of this treaty, the IBC was renamed the International Boundary and Water Commission (IBWC). It also expanded the commission’s duties and made changes to its leadership structure.
Pursuant to the 1944 treaty, the IBWC has the status of an international body and consists of a United States Section and a Mexican Section. Each section is headed by an engineer commissioner and includes two principal engineers, a legal adviser and a secretary who are entitled diplomatic privileges and immunities. The IBWC and its personnel may freely carry out their observations, studies and field work in the territory of the other country. Wherever there are provisions for joint action or joint agreement of the two governments or for the furnishing of reports, studies or plans, it is stipulated that those matters will be handled by the US State Department and the Ministry of Foreign Relations of Mexico.
The 1944 treaty further provided for the two governments to jointly construct, operate and maintain dams on the Rio Grande required for conservation, storage and regulation of water. Furthermore, the 1944 treaty established a guaranteed annual quantity of 1.5 million acre-feet to Mexico, and authorized the construction of a canal by Mexico to divert water from the Colorado River below the point where the California-Baja California land boundary line intersects the river. It also provided for the construction of flood control facilities, at Mexico’s expense, to protect US lands from floods that might result from the operation of the diversion canal.
Other key agreements include the
Chamizal Convention of August 29, 1963 (PDF), which resolved a 100-year-old boundary dispute between El Paso and Juárez, Chihuahua. The
Treaty of November 23, 1970 (PDF) included provisions for restoring and preserving the character of the Rio Grande, to minimize changes in the channel and to resolve problems of sovereignty that arise due to future changes in the channel.