Petróleos Mexicanos or Pemex (Spanish pronunciation: [ˈpemeks], Mexican Petroleum), headquartered in Mexico City,[2] is Mexico's state-owned petroleum company. It is the second largest oil company in the world in terms of revenue and ranks as the 4th larget company in the world by total revenue.[3]
Asphalt and pitch had been worked in Mexico since the time of the Aztecs. Small quantities of oil were first refined into kerosene around 1876 near Tampico. By 1917 commercial quantities of oil were being extracted and refined by subsidiaries of the British Pearson and American Doheny companies, and had attracted the attention of the Mexican government who then claimed all mineral rights for the state as part of its Constitution.
Source: http://en.wikipedia.org/wiki/Pemex
