Whose frontier? The Mexican‐United States border in perspective

Abstract

Giving preference to Spanish and Mexican primary sources and recent Mexican historiography, this essay examines the oft‐repeated statement that Mexico lost half or more of her territory to the United States between 1848 and 1853. The European‐African conquest of what is now Mexico was a gradual process starting in 1519 and ending in the early years of the twentieth century with the surrender of rebel groups of Mayas, Yaquis, Apaches, and others. The boundary fixed by the Adams‐Onis treaty in 1819, separating the territorial pretensions of Spain and the United States, passed through existing native polities which were quite independent of either power. At the beginning of the war of 1846–48 the Mexican government controlled approximately 656,400 square miles, of which roughly 45,000 square miles in Alta California, Sonora, Nuevo Mexico and Tamaulipas were annexed to the United States between 1848 and 1853. Subsequently, the Indians on both sides of the new frontier were subdued or exterminated and their lands were occupied by Anglo and Hispano colonists. The present land area of Mexico, 761,680 square miles, is appreciably greater than in 1846. During the past century‐and‐a‐half, the human population of the area between the 1819 and 1853 treaty lines has soared from about 672,000 in 1846 to almost sixty million today, of whom about a quarter are of ‘Hispanic’ origin, most of them recent migrants from Mexico.