In 1921 Mexico produced a quarter of the world’s petroleum, making the country the second largest producer in the world, but by 1930 it only accounted for 3 per cent of production. To date, the debate surrounding this decline has relied mainly on events taking place in Mexico. Very little attention has been paid to developments elsewhere in the petroleum industry, except in Venezuela. Practically no attention has been paid to the reasons for the rise of oil output in Mexico. The massive changes which took place in the petroleum industry during the Great War years and its aftermath and especially the shortage of oil which occurred on world markets between 1918 and 1921 have been neglected. These events are crucial in order to unders...