Longest time in power for a political party

The Institutional Revolutionary Party (PRI) is a Mexican political party founded in 1929, which remained in power uninterruptedly in Mexico for 71 years (1929–2000). Although it was originally called the National Revolutionary Party, the party changed its name to the Party of the Mexican Revolution in 1938 and in 1946 settled on the Institutional Revolutionary Party. The first four decades of government of the PRI have been called the "Mexican Miracle", a period of economic growth nurtured by a high level of imports and low inflation.