Editing Gadsden Purchase (section)

=== Post-ratification controversy ===
As originally envisioned, the purchase would have encompassed a much larger region, extending far enough south to include most of the current [[List of states of Mexico|Mexican states]] of [[Baja California]], [[Baja California Sur]], [[Coahuila]], [[Chihuahua (state)|Chihuahua]], [[Sonora]], [[Nuevo León]], and [[Tamaulipas]]. The Mexican people opposed such boundaries, as did [[Abolitionism in the United States|anti-slavery Americans]], who saw the purchase as acquisition of more slave territory. Even the sale of a relatively small strip of land angered the Mexican people, who saw Santa Anna's actions as a betrayal of their country. They watched in dismay as he squandered the funds generated by the Purchase. Contemporary Mexican historians continue to view the deal negatively and believe that it has defined the American–Mexican relationship in a deleterious way.<ref name="azstar" />

The purchased lands were initially appended to the existing New Mexico Territory. To help control the new land, the [[United States Army|US Army]] established [[Fort Buchanan, Arizona|Fort Buchanan]] on [[Sonoita Creek]] in present-day southern Arizona on November 17, 1856. The difficulty of governing the new areas from the territorial capital at [[Santa Fe, New Mexico|Santa Fe]] led to efforts as early as 1856 to [[Territories of the United States|organize a new territory]] out of the southern portion. Many of the early settlers in the region were, however, pro-slavery and sympathetic to the [[Southern United States|South]], resulting in an impasse in Congress as to how best to reorganize the territory.

The shifting of the course of the [[Rio Grande]] would cause a later dispute over the boundary between Purchase lands and those of the state of Texas, known as the [[Country Club Dispute]]. Pursuant to the Treaty of Guadalupe Hidalgo, the Gadsden Treaty and subsequent treaties, the [[International Boundary and Water Commission]] was established in 1889 to maintain the border. Pursuant to still later treaties, the IBWC expanded its duties to allocation of river waters between the two nations, and provided for flood control and water sanitation. Once viewed as a model of international cooperation, in recent decades the IBWC has been heavily criticized as an institutional anachronism, by-passed by modern social, environmental, and political issues.<ref>{{cite journal |first=Robert J. |last=McCarthy |title=Adaptive Treaty Interpretation, and the International Boundary and Water Commission |ssrn=1839903 |journal=Water Law Review |date=May 12, 2011}}</ref>