Petroleos Mexicanos - Pemex
In the early years of the Twentieth Century American wildcatters began exploring the Mexican Gulf coastline but it bwas not until 1910 that the business boomed after British engineer Weetman Pearson struck oil at the legendary Potrero del Llano No. 4 well. While the then President of Mexico encouraged foreign business in Mexico, the revolution in 1917 changed everything, declaring that the oil belonged to Mexico. This was not enforced until 1938 when President Lazaro Cardenas nationalised all the countries oil holdings and created a national oil company - Petroleos Mexicanos. A major new strike in 1972 bolstered the struggling company and by the early 1980s Pemex was funding half of the Mexican government budget. Corruption and trade unions proved to be problems in the 1980s while in 1992 an explosion in Guadalajara resulted in four Pemex executives being jailed.