Bloody Political Strife and Trouble with the U.S.
The years after the fall of the dictator Porfirio Diaz (1877–1880 and 1884–1911) were marked by bloody political-military strife and trouble with the U.S., culminating in the punitive U.S. expedition into northern Mexico (1916–1917) in unsuccessful pursuit of the revolutionary Pancho Villa. Since a brief civil war in 1920, Mexico has enjoyed a period of gradual agricultural, political, and social reforms. The Partido Nacional Revolucionario (PNR; National Revolutionary Party), dominated by revolutionary and reformist politicians from northern Mexico, was established in 1929; it continued to control Mexico throughout the 20th century and was renamed the Partido Revolucionario Institucional (PRI; Institutional Revolutionary Party) in 1946. Relations with the U.S. were disturbed in 1938 when all foreign oil wells were expropriated, but a compensation agreement was reached in 1941.