American-Mexican Boundary Disputes and Co-operation

Abstract

Abstract The first Mexican–United States boundary had its origin in the 1819 Treaty of Amity, Settlement, and Limits Between the United States of America and His Catholic Majesty (‘Adams-Onís Treaty’ ‘Florida Purchase Treaty’) by which Spain ceded Florida and confirmed Louisiana as a US territory in exchange for which the US recognized all lands west of Louisiana as Spanish possessions (→ Boundaries; → Land Boundaries). This line of demarcation became the new Mexico–US boundary upon Mexican independence in 1821, and was reconfirmed in the Treaty of Limits between the United States of America and the United Mexican States as running from the Gulf of Mexico along the Sabine, Red, and Arkansas Rivers to the 42nd parallel, and along that line to the Pacific Ocean. The boundary underwent a first major adjustment in the wake of civil unrest in the Mexican state of Coahuila y Tejas. A combination of factors including abolition of the Mexican federalist constitution and Mexican authorities’ clamp-down on American immigration into the Texas portion of the state, which had been prompted by governmental concern over the creeping ‘Americanization’ of the territory, caused its inhabitants to take up arms in 1835 and declare the territory’s independence in May 1836.