On March 18, 1938, Mexican President Lazaro Cardenas signed an order that expropriated the assets of nearly all of the foreign oil companies operating in Mexico. He later created Petroleos Mexicanos (PEMEX), a state-owned firm that held a monopoly over the Mexican oil industry, and barred all foreign oil companies from operating in Mexico.
Since Mexico was an agrarian nation with only a tiny domestic market, these companies exported most of the oil they produced during the 1920s and very little of their profits remained Mexico. The situation was exacerbated during the 1930s, when the Mexican Government's share of oil revenues declined and domestic oil production dropped due to the Great Depression and a glut in the global oil supply. These developments, combined with the fact that the large oil companies often paid their Mexican workers only half as much as other employees working in the same capacity, ultimately led to massive labor unrest.
A strike by oil workers in 1937 ultimately led the Mexican Government to act. Initially, President Cardenas attempted to mediate a settlement by having a government commission draw up a new labor agreement. After the foreign companies defied both the commission and the Mexican Supreme Court, however, Cardenas promulgated the expropriation decree on March 18, 1938. The expropriation act had international repercussions. The foreign-owned oil companies retaliated by instituting an embargo against Mexican oil. Mexican oil exports decreased by 50% and the Mexican Government's primary customer for oil became Nazi Germany. Expropriation also led the British, who had counted upon Mexican and Venezuelan oil exports in the event of a war with Germany, to sever diplomatic relations with Mexico.
The U.S. Ambassador in Mexico realized that such action might provoke a diplomatic rupture and asked the Mexicans to consider the note undelivered until a more moderate policy could be formulated in Washington. Further opposition from the Treasury Department eventually forced Hull and the State Department to back down. Although Hull's attempts to directly challenge the Mexican Government fell out of favor, U.S. companies fought the expropriation in their own way. For over two years following expropriation, the oil companies made extravagant demands for compensation, which the Mexicans repeatedly rejected.
The U.S. Government supported the oil companies until the Second World War began in Europe, at which point it pressured them to accept a settlement. Finally, on April 18, 1942, the U.S. and Mexican Governments signed the Cooke-Zevada Agreement, whereby the Mexicans agreed to pay roughly $29 million in compensation to several American firms, including Jersey Standard and Socal. The British, however, held out until 1947, when they received $130 million. Efforts to secure the re-admission of the foreign oil companies in Mexico proved to be a failure, however. After Cardenas left office in 1940, the Mexicans were willing to consider the possibility, but only on condition that Mexico retained ownership of the subsoil, and PEMEX its domestic monopoly. This proved unacceptable to both the U.S. Government and oil companies. Finally, in 1950, the U.S. Government abandoned its efforts to re-open the Mexican oil industry after several failed attempts to use government