Cession

The act of cession is the assignment of property to another entity. In international law it commonly refers to land transferred by treaty. Ballentine's Law Dictionary defines cession as "a surrender; a giving up; a relinquishment of jurisdiction by a board in favor of another agency" In contrast with annexation, where property is forcibly given up, cession is voluntary or at least apparently so.

Examples

In 1790, the U.S. states of Maryland and Virginia both ceded land to create the District of Columbia, as specified in the U.S. Constitution of the previous year. The Virginia portion was given back in 1847, a process known as "retrocession".

Following the First Opium War (1839–1842) and Second Opium War (1856–1860), Hong Kong (Treaty of Nanking) and Kowloon (Convention of Peking) were ceded by the Qing dynasty government of China to the United Kingdom; and following defeat in the First Sino-Japanese War, Taiwan was ceded to the Empire of Japan in 1895.

Territory can also be ceded for payment, such as in the Louisiana Purchase and Alaska Purchase.

Mexican Cession

The Mexican Cession of 1848 is a historical name in the United States for the region of the modern day southwestern United States that Mexico ceded to the U.S. in the Treaty of Guadalupe Hidalgo in 1848, but had not been part of the areas east of the Rio Grande which had been claimed by the Republic, though the Texas annexation resolution two years earlier had not specified Texas's southern and western boundary. The Mexican Cession (529,000 sq. miles) was the third largest acquisition of territory in US history. The largest was the Louisiana Purchase, with some 820,000 sq. miles, followed by the acquisition of Alaska (about 586,000 sq. miles).

Extent

Most of the area had been the Mexican territory of Alta California, while a southeastern strip on the Rio Grande had been part of Santa Fe de Nuevo Mexico, most of whose area and population were east of the Rio Grande on land that had been claimed by the Republic of Texas since 1835, but never controlled or even approached aside from the Texan Santa Fe Expedition. Mexico controlled the territory later known as the Mexican Cession, with considerable local autonomy punctuated by several revolts and few troops sent from central Mexico, in the period from 1821–22 after independence from Spain up through 1846 when U.S. military forces seized control of California and New Mexico on the outbreak of the Mexican–American War. The northern boundary of the 42nd parallel north was set by the Adams–Onís Treaty signed by the U.S. and Spain in 1821 and ratified by Mexico in 1831. The eastern boundary of the Mexican Cession was the Texas claim at the Rio Grande and extending north from the headwaters of the Rio Grande, not corresponding to Mexican territorial boundaries. The southern boundary was set by the Treaty of Guadalupe Hidalgo, which followed the Mexican boundaries between Alta California (to the north) and Baja California and Sonora (to the south)