The Anniversary of the Oil Expropriation in Mexico is observed every March 18, celebrating the nationalization of the country's oil industry by President Lázaro Cárdenas in 1938. This holiday marks a significant shift from foreign control of oil drilling to national ownership, as prior to 1938, oil was primarily extracted by foreign companies. The expropriation aimed to revitalize Mexico's economy, especially as oil fields began to decline after 1923 and U.S. investments shifted to Venezuela. Although the legislation provided for financial compensation to the expropriated companies, Cárdenas faced backlash from the international business community. Despite initial challenges in managing the oil refiners, Mexico successfully resumed oil production, reaching pre-nationalization levels by 1942, aided by technical advisers from the United States. The establishment of Pemex (Petróleos Mexicanos) by Cárdenas serves as a model for other nations seeking greater control over their oil and natural gas resources.