During that war, topographical officers William H. Emory and James W. Abert had conducted surveys that demonstrated the feasibility of a railroad's originating in El Paso or western Arkansas and ending in San Diego.

[12] He was concerned that the increasing railroad construction in the North was shifting trade in lumber, farm and manufacturing goods from the traditional north–south route based on the Ohio and Mississippi rivers to an east–west axis that would bypass the South.

The Memphis convention overwhelmingly advocated the construction of a route beginning there, to connect with an El Paso, Texas to San Diego, California line.

The convention president, Matthew Fontaine Maury of Virginia, preferred strict private financing, whereas John Bell and others thought that federal land grants to railroad developers would be necessary.

Gadsden planned to establish a slave-holding colony there based on rice, cotton, and sugar, and wanted to use slave labor to build a railroad and highway that originated in either San Antonio or the Red River valley.

[15] A few months later, Gadsden and 1,200 potential settlers from South Carolina and Florida submitted a petition to the California legislature for permanent citizenship and permission to establish a rural district that would be farmed by "not less than Two Thousand of their African Domestics".

Moreover, the Compromise of 1850 encouraged Southerners not to antagonize opponents by resurrecting the railroad controversy.The Treaty of Guadalupe Hidalgo (1848) ended the Mexican–American War, but left issues affecting both sides that still needed to be resolved: possession of the Mesilla Valley, protection for Mexico from Indian raids, and the right of transit in the Isthmus of Tehuantepec.

The treaty provided for a joint commission, made up of a surveyor and commissioner from each country, to determine the final boundary between the United States and Mexico.

[22] John Bartlett of Rhode Island, the United States negotiator, agreed to allow Mexico to retain the Mesilla Valley by setting the point at which the boundary commenced toward the west from the Rio Grande River at 32° 22′ N. This point was north of the American claim of 31° 52′ N and, at the easternmost part, also north of the Mexican-claimed boundary at 32° 15′ N, both also on the Rio Grande River[23]).

[24] Article XI of the Treaty of Guadalupe Hidalgo contained a guarantee that the United States would protect Mexicans by preventing cross-border raids by local Comanche and Apache tribes.

[3] Historian Richard Kluger, however, described the difficulties of the task: Comanche, Apache, and other tribal warriors had been punishing Spanish, Mexican, and American intruders into their stark homeland for three centuries and been given no incentive to let up their murderous marauding and pillaging, horse stealing in particular.

The U. S. Army had posted nearly 8,000 of its total of 11,000 soldiers along the southwestern boundary, but they could not halt the 75,000 or so native nomads in the region from attacking swiftly and taking refuge among the hills, buttes, and arroyos in a landscape where one's enemies could be spotted twenty or thirty miles away.

Interests in Louisiana were especially adamant about this option, as they believed that any transcontinental railroad would divert commercial traffic away from the Mississippi and New Orleans, and they at least wanted to secure a southern route.

[25] In Mexico, topographical officer George W. Hughes reported to Secretary of State John M. Clayton that a railroad across the isthmus was a "feasible and practical" idea.

Judah P. Benjamin and a committee of New Orleans businessmen joined with Hargous and secured a charter from the Louisiana legislature to create the Tehuantepec Railroad Company.

Some southerners, however, worried that northern and central interests would leap ahead in construction and opposed any direct aid to private developers on constitutional grounds.

[33] This rejection led to legislative demands, sponsored by William Gwin of California and Salmon P. Chase of Ohio and supported by the railroad interests, for new surveys for possible routes.

[34] A treaty initiated in the Fillmore administration that would provide joint Mexican and United States protection for the Sloo grant was signed in Mexico on March 21, 1853.

Roberson wrote:[7] The unfortunate debates in 1854 left an indelible mark on the course of national politics and the Pacific railroad for the remainder of the antebellum period.

Although few people fully realized it at the close of 1854, sectionalism had taken such a firm, unrelenting hold on the nation that completion of an antebellum Pacific railroad was prohibited.

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.

By the late 1850s mining camps and military posts had not only transformed the Arizona countryside; they had also generated new trade linkages to the state of Sonora, Mexico.

Magdalena, Sonora, became a supply center for Tubac; wheat from nearby Cucurpe fed the troops at Fort Buchanan; and the town of Santa Cruz sustained the Mowry mines, just miles to the north.

After the Gadsden Purchase, southern Arizona's social elite, including the Estevan Ochoa, Mariano Samaniego, and Leopoldo Carillo families, remained primarily Mexican American until the coming of the railroad in the 1880s.

A biographical analysis of some 200 of its employees, classed as capitalists, managers, laborers, and general service personnel, reveals that the resulting work force included Europeans, Americans, Mexicans, and Indians.

This mixture failed to stabilize the remote area, which lacked formal social, political, and economic organization in the years from the Gadsden Purchase to the Civil War.

[59] Federal and private surveys by Lt. John G. Parke and Andrew B Gray proved the feasibility of the southern transcontinental route, but sectional strife and the Civil War delayed construction of the proposed railroad.

Acquiring trackage rights over the SP, from Deming to Benson, the Santa Fe then built a line southwest to Guaymas, Sonora, Mexico, completed October 1882, as its first outlet to the Pacific.

[67] This rugged terrain above the Gila River confirms the engineering, technical wisdom of acquiring the Gadsden Purchase for a southern transcontinental railroad.

[71] The consequences of the Gadsden Purchase for Mexicans and Native Americans living in the region form the background of the story in the film Conquest of Cochise (Columbia, 1953).