The Origins of the McLane–Ocampo Treaty of 1859
The treaty of Guadalupe Hidalgo in 1848 acquired for the United States one-half of Mexican territory, while the Gadsden Purchase of 1853 secured a more level route for railroads destined to connect the south and the far west. Impatient investors, however, sought immediate union with the west, and the shortest route at hand was across the isthmus of Tehuantepec in southern Mexico. The Department of State advanced these interests, and only on failure turned their efforts to an overland route across Northern Mexico. This latter route would have connected Matamoros on the Rio Grande and Atlantic with Matzatlan on the Pacific. To this goal, Delphy Carlin, an American long-experienced in trade with Mexico, urged Secretary of State Lewis Cass. He was convinced that a line skirting the mountains and connecting these ports would be an ideal boundary; that “all north of that red line is a nuisance to Mexico.”