Mexico underwent notable changes during the Mexican War of Independence, which stretched from 1810 to 1821. On mainland Mexico, Hidalgo led the independence movement against Spanish dominance in New Spain. In particular, Hidalgo championed the political and economic freedoms of the region as well as racial equality for Indians, mestizos, criollos, and peninsulares. Although Hidalgo himself did not survive past 1811, the revolutionary movement continued with guerrilla bands and some constitutional attempts. The Spanish crown signed the Treaty of Córdoba on September 27, 1821, recognizing Mexican independence. The Treaty of Córdoba  enforced the Plan of Iguala, which made the following guarantees:

  • Mexico would be recognized as an independent monarchy governed by a relocated King Ferdinand or other European prince
  • Criollos and peninsulares would now enjoy equal rights and privileges
  • The Roman Catholic Church would remain the religious monopoly.

Throughout the Mexican War of Independence, Baja was involved but isolated from the hostilities incurred. At the war’s conclusion, President Guadalupe Victoria and Governor José María Echeandía partitioned the Baja region into four municipalities. Loreto, the oldest sustained colony in the region, remained the capital until 1830 when it was shifted to La Paz due to heavy rainfall. La Paz remains the capital to this day.

In a similar fashion to the Mexican War of Independence, Baja California saw little military action in the subsequent Mexican-American War from 1846-1848. An American flag flew briefly over La Paz and Pichilinque in 1847. Pichilinque was seized as a base for U.S. naval operations, and after the war concluded the U.S. continued to lease the land to use as a coaling station until after WWII. In La Paz, the U.S. garrison was attacked and sieged much like other U.S. positions throughout Baja. Although Mexican forces vandalized and plundered La Paz before their withdrawal from the city, Baja remained relatively calm until the Treaty of Guadalupe Hidalgo on February 2, 1848.

The Treaty of Guadalupe Hidalgo defined the future of Baja in that it did not include Baja’s annexation into America despite President Polk’s previously fervent promises to include the region in the land successions. With many residents hoping for annexation, Baja waved goodbye to a large group of evacuated refugees who left in favor of the California territories after the war’s conclusion.

Despite the acknowledged agreement of the treaty, American journalist William Walker led an ill-fated group of forty five mercenaries to recapture the City of La Paz in 1853. Walker arrested La Paz’s governor, possessed the government buildings, and even raised a flag of a new republic over the town—a republic of which he was president. The U.S. government did not officially support or condone this invasion, and without the support the Mexican army quickly drove out Walker and his supporters.

Although Baja remained secluded from conflicts and political turmoil throughout most of the 19th century, it became more involved in the Mexican Revolution in the early 20th century. The Mexican Revolution, which established a constitutional republic, started in 1910 against the rule of Porfirio Díaz. In particular, Baja California was a successful base for the Liberal Party of Mexico and even the site of the 1911 anarchist Magonista Rebellion. The revolution concluded in 1921 with Baja supporting Venustiano Carranza, the republic’s new president. Baja California became Mexico’s 29th state in 1952, and Baja California Sur followed in 1974.