From Empire to Republic - Arthur H. Noll

Appendix C:


A study of the historical geography of Mexico properly begins with a consideration of Spain's possessions on the North American continent prior to the year 1821.

It was about the middle of the eighteenth century that Spanish territory in North America reached its maximum extent. With the changes which subsequently took place in the northern boundaries on the Atlantic coast, we have little to do, for Florida was not a part of New Spain. On the Pacific coast, Spain claimed all the territory from Panama to Prince William's Sound, though no permanent settlements had been made north of San Francisco. By the Treaty of Nootka (1790), to which Spain and England were parties, the former renounced all sovereignty to the North Pacific coast. Subsequently (1795), she fixed the limits of her territory on what is now the northern boundary of California.

By the Treaty of Ildefonso in 1802, Spain gave up to France the Territory of Louisiana, which had been hers since 1760. Napoleon, the following year, sold Louisiana to the United States. Spain and France were at the time rival claimants to the territory lying west of the Sabine River in Texas, and the United States succeeded, by the terms of the purchase, to the claim of France in that territory. It was not until 1819 that the boundary line between the United States and the northern provinces of New Spain was established, and then it was as one of the terms of the Treaty by which the United States effected the purchase of Florida.

This boundary line began at the mouth of the Sabine River and ascended that river to the thirty-second parallel of north latitude; thence it ran due north to the Red River; thence up the river to a point one hundred degrees west of Greenwich; thence due north to the Arkansas River and up that river to its head; thence to the forty-second parallel of latitude; thence along that line, which was the line adopted by Spain in 1795, to the Pacific Ocean. This line, so far as it affected the boundary of Texas, was affirmed in a treaty with Mexico in 1828 and tea years later in a treaty with the Republic of Texas.

The blue line on the accompanying map shows the extent of territory comprised in the First Mexican Empire and in the United States of Mexico up to the year 1836. In that year Texas revolted and established her independence of Mexico. The boundaries of the new Republic of Texas were by no means clearly defined and the lands between the Rio Grande and the Rio Nueces were in dispute between Mexico and Texas. A further dispute would undoubtedly have arisen in regard to the western boundary of Texas had not the war between the United States and Mexico resulted in the loss to Mexico of the territory including the dubious boundary line. A green line upon the accompanying map indicates the boundary of Mexico after the revolt of Texas, according to the claims of the latter.

By the Treaty of Guadalupe-Hidalgo at the close of the war with the United States in 1848, the northern boundary of Mexico was established upon the Gila River and extended eastward to the Rio Grande, and down the Rio Grande to its mouth, as indicated by a red line upon the accompanying map.

By a treaty concluded in 1853, with James Gadsden representing the United States, Mexico sold to the latter a tract south of the Gila River which is known historically as the "Gadsden Purchase," and is indicated upon the accompanying map by a red tint. Thus the northern boundary of Mexico became fixed as it is to-day.

It is in no way remarkable that, after the loss of so much territory, the "maintenance of the territorial integrity of Mexico" should become one of the fixed principles of government in that country, answering to the "Monroe Doctrine" in the United States in the tenacity with which it is held, the emphasis with which it is asserted, and, it might be added, the curious manner in which it has sometimes been applied in political argument.