ضم تكساس وكاليفورنيا ونيومكسيكو للولايات المتحدة 1845- 1848

     On February 2, 1848, the United States and Mexico signed the Treaty of Guadalupe Hidalgo, which put an official end to the Mexican–American war  (1846-1848). By its terms, a vast area of Mexican territory amounting to about 918,000 miles, including California, New Mexico was ceded to the United States. In addition, the treaty recognized the Rio Grande River as a boundary for Texas for a payment of $15 million to be paid by the United States to Mexico. The treaty also added areas to the United States territory including the land of present-day Arizona, New Mexico and California, as well as parts of the states of Colorado, Wyoming, Utah and Nevada. In 1853, the United States signed the Gadsden Purchase  (or the Treaty of La Mesilla), which assigned to the United States nearly 29,670,000 miles of Mexican territory. With these two agreements, the continental expansion phase was completed, which began with the Louisiana Purchase 1803, passed through the annexation of Florida in1819 and then Oregon in 1846, in which the American expansion was limited to the territorial scope of the United States to begin a new phase of an expansion outside the United States, that is, the Pacific ocean phase.
    The research deals with the United States position on the revolutions in South America, and its position on the Texas revolution against the Mexican rule and the Texas’s request to be annexed to United States. Furthermore, the research explores the factors that prompted the United States to agree to the annexation after hesitation, the border dispute between the United States and Mexico over the Texas border and the tension between the two countries that caused the war between them, which ended with the victory of the United States, and the signing of the Treaty of Guadalupe Hidalgo, and the implications.