Most of the country is subject to humid trade winds from the east between May and August and tropical hurricanes from August to October. Crude oil accounts for a majority of Mexico's foreign earnings, and oil revenues have been used to develop an industrial base. There is considerable mineral wealth, particularly oil reserves, silver, and zinc, as well as uranium and copper, not all of which has been fully exploited. Mexico supplies a quarter of the world's requirements in fluorspar. Mexico's main exports are chemicals, non-ferrous ores, motor vehicles, and petroleum products.
Agriculture relies on irrigation.
The main food crop is maize, and export crops include fruit, vegetables, and coffee. In 1993, Mexico concluded the North American Free Trade Agreement with the USA and Canada. Mexico City is the world's largest urban centre, with severe problems of pollution, infrastructure, and overcrowding. A rigid colonial administration, including repression and exploitation of the native population, lasted for the next 300 years. As many as 90 per cent of the indigenous population had died of European-introduced diseases by the early 17th century, and thereafter their numbers only slowly increased.