The Mexican oil expropriation () was the nationalization of all petroleum reserves, facilities, and foreign oil companies in Mexico on March 18, 1938. In accordance with Article 27 of the Constitution of 1917, President Lázaro Cárdenas declared that all mineral and oil reserves found within Mexico belong to "the nation", i.e., the federal government. The Mexican government established a state-owned petroleum company, Petróleos Mexicanos, or PEMEX. For a short period, this measure caused an international boycott of Mexican products in the following years, especially by the United States, the United Kingdom, and the Netherlands, but with the outbreak of World War II and the alliance between Mexico and the Allies, the disputes with private companies over compensation were resolved. The anniversary, March 18, is now a Mexican civic holiday. Background On August 16, 1935, the Petroleum Workers Union of Mexico (Sindicato de Trabajadores Petroleros de la República Mexicana) was formed and one of the first actions was the writing of a lengthy draft contract transmitted to the petroleum companies demanding a 40-hour working week, a full salary paid in the event of sickness, and the payment of 65 million pesos towards benefits and wages. The foreign oil companies refused to sign the agreement, and counter offered with a payment of 14 million pesos toward wages and benefits. On November 3, 1937, the union demanded that the companies sign the collective agreement and on May 17, the union summoned a strike in case their demands were not met. On May 28 the strike became effective throughout the country. The petroleum workers' struggle was well regarded by the President and the population despite problems caused by the petroleum shortage. Due to these problems, the union accepted a lift of the strike on June 9, after the president urged them to present their case before the General Arbitration and Conciliation Board (Junta General de Conciliación y Arbitraje). In July, as instructed by the arbitration board, a commission of financial experts was formed that investigated the petroleum companies' finances, concluding that their profits easily permitted them to cover the demands of the workers. The report stated that just one company (El Aguila) had received annual profits of over 55 million pesos. The arbitration board concluded that the oil companies should pay 26 million pesos for wages and benefits to the workers. The companies, however, insisted the demands would cripple production and bankrupt them, and