Editing 1840s (section)

==== Mexican–American War ====
{{Main|Mexican–American War}}[[File:Battle Molino del Rey.jpg|thumb|right|250px|[[Mexican–American War]]]] [[Territorial expansion of the United States|American territorial expansion]] to the [[Pacific coast of the United States|Pacific coast]] was a major goal of U.S. President [[James K. Polk]].<ref>{{Cite book|url=https://books.google.com/books?id=vfhAAAAAIAAJ&pg=PA658|title=The United States and Mexico, vol. 2|last=Rives|year=1913|pages=658}}</ref> In 1845, the United States of America [[Texas Annexation|annexed Texas]], which had won independence from [[Centralist Republic of Mexico]] in the [[Texas Revolution]] of 1836. Mexico did not accept the annexation, while also continuing to claim the [[Nueces River]] as its border with Texas<s>,</s> and also still considering Texas to be a province of Mexico. In 1845, newly elected U.S. President [[James K. Polk]] sent troops to the disputed area, and a diplomatic mission to Mexico. After Mexican forces [[Thornton Affair|attacked American forces]], the U.S. declared the [[Mexican–American War]] (1846–1848).

Combat operations lasted a year and a half, from the spring of 1846 to the fall of 1847. U.S. forces quickly occupied the capital town of [[Santa Fe de Nuevo México]] along the upper Rio Grande and began the [[Conquest of California]] in Mexico's [[Alta California]] Department. They then invaded to the south into parts of central Mexico (modern-day northeastern Mexico and northwest Mexico). Meanwhile, the [[Pacific Squadron]] of the [[United States Navy]] conducted a blockade and took control of several garrisons on the [[Pacific Ocean|Pacific]] coast farther south in lower [[Baja California Territory]]. The U.S. Army eventually captured the capital [[Mexico City]], having marched west from the port of [[Veracruz (city)|Veracruz]], where the Americans staged their first amphibious landing on the [[Gulf of Mexico]] coast.

The 1848 [[Treaty of Guadalupe Hidalgo]], forced onto the remnant Mexican government, ended the war and specified its major consequence, the [[Mexican Cession]] of the northern territories of Alta California and Santa Fe de Nuevo México to the United States. The U.S. agreed to pay $15 million compensation for the physical damage of the war. In addition, the United States assumed $3.25 million of debt already owed earlier by the Mexican government to U.S. citizens. Mexico acknowledged the loss of their province, later the Republic of Texas (and now the [[Texas|State of Texas]]), and thereafter cited and acknowledged the Rio Grande as its future northern national border with the United States. Including Texas, Mexico ceded an area of approximately {{convert|2500000|km2}} – by its terms, around 55% of its former national territory.<ref>{{cite news|url=http://www.ourdocuments.gov/doc.php?flash=true&doc=26|title=Treaty of Guadalupe Hidalgo (1848)}}</ref>