In the summer of 1810 the American set lers in West Florida revolted against Spain, established an independent government and requested to be annexed to the United States. On 27 Oct. 1810, President Madison issued a proclamation stating that he "deemed it right and requisite that possession should be taken of the said territory in the name and behalf of the United States,* and sent William C. C. Claiborne to take possession. Congress passed a bill (signed 15 Jan. 1811) authorizing the President to take and hold East Florida also, if the local authorities were willing or if a foreign power should attempt to occupy it. Thus the United States claimed all the ter ritory from the Mississippi to the Perdido, though her authority did not extend to Mobile and she was not even ready to enforce author ity to the Pearl. On 20 Feb. 1811 a bill was signed by the President authorizing the Ter ritory of Orleans to form a constitution and apply for admission as a State. The con stitution was framed and the act to admit Louisiana was passed 8 April 1812. The eastern States objected, whereupon Congress (14 April 1812) passed an act enlarging the State. Acting on the principle that West Florida, which had been seized because it was a part of Louisiana, should be treated as con quered territory, Congress divided the district into two halves at the Pearl River and annexed the western half to Louisiana. The eastern portion was incorporated in the Mississippi Territory by an act approved 14 May 1812. Soon a revolution was organized and the city of Fernandina was seized and occupied, but though Spain protested she was too weak to do more and as the War of 1812 occupied the attention of the United States, the matter rested in abeyance for a long time, the situa tion being further complicated by Jackson's capture of Pensacola in 1814 and 1818, the Amelia Island imbroglio, the Seminole War, and the Arbuthnot-Ambrister affair. Finally on 22 Feb. 1819, a treaty was concluded with Spain to purchase Florida (though not rati fied by Spain until 24 Oct. 1820), and on 3 March 1821, Congress authorized the Presi dent to take possession of East and West Florida and to establish a government therein. Thus for $5,000,000 and the abandonment of all claims to Texas the United States secured full title to both East and West Florida and thereby settled the southern boundary dispute. As defined in the treaty, the boundary line between the two countries, west of the Missis sippi, was to begin at the mouth of the Sabine River (the present western boundary of Louisiana), up that river to the Red River, and along that river to the 100th meridian; from that point due north to the Arkansas River, and following the southern bank of that river to its source in latitude 42° north and thence by that parallel of latitude (the present northern boundary of California) to the Pacific Ocean. All the islands in the
Sabine, Red and Arkansas rivers were to belong to the United States.
There was a widespread feeling in the United States that the government could have claimed Texas to the Rio Grande as a part of the Louisiana Purchase. Attempts were made by Clay when Secretary of State and later by President Jackson to substitute the Rio Brazos, or the Rio Colorado, or even the Rio Grande as a boundary in place of the Sabine, or to purchase a part of Texas east of the Colorado, but Mexico, having then become independent of Spain, rejected all offers, and the boundary remained unchanged and uncontroverted until after Texas had entered the Union. As a republic Texas claimed the Rio Grande as its boundary, but as a previous state of the Mexican Republic it extended only as far as the Nueces River. In 1800 the Rio Grande constituted the old boundary of Texas and as Texas still claimed it, the American gov ernment re-asserted it and the denial of the claim by Mexico was the immediate cause of the Mexican War of 1846-48. (See also UNITED STATES - THE . ANNEXATION OF TEXAS ; UNITED STATES - THE MEXICAN WAR). The war was terminated by the treaty of Guadalupe-Hidalgo 2 Feb. 1848, under which, on the payment of $15,000,000, Mexico ceded to the United States all territory north of the Rio Grande and Gila rivers, in cluding Arizona, New Mexico, California, Utah, Nevada, and parts of Colorado Wyoming, in all about 525,000 square miles. One part of the boundary was to run along the western boundary of New Mexico, but as it proved difficult to locate the boundaries of old New Mexico that part of the line was never run, hut under the so-called Gadsden treaty (q.v.) of 30 Dec. 1853 the boundary between the two countries was to begin — "in the Gulf of Mexico, three leagues from land. opposite the mouth of the Rio Grande. as provided in the article of the treaty of Guadalupe-Hida ; thence, as defined in the said article, up the middle of that river, to the point where the parallel 47' north latitude crosses the same; thence due west one hundred miles; thence south to the parallel of 31° 20' north latitude; thence along the said parallel of 31° 20' to the 111th meridian of longitude west ofGreenwich; thence in a straight line to a point on the Colorado River twenty English miles below the junction of the Gila and Colorado Rivers; thence up the middle of the said river Colorado until it intersects the present line between the United States and Mexico." Thus the southern and southwestern boundaties of the United States were completed and the only boundary difficulty still to be adjusted is a local question on the Rio Grande.