Which party dominated Mexican politics and maintained a monopoly until challenges emerged in the late 20th century?

• A. PRD
• B. PRI
• C. PAN
• D. MORENA

Answer: (B)

The Institutional Revolutionary Party, or PRI, dominated Mexican politics for much of the 20th century by combining a broad revolutionary legacy with tight control over political institutions and powerful patronage networks. After the Mexican Revolution, the PRI formed a big umbrella that brought together competing factions and built a centralized system that could mobilize rural, labor, and business sectors behind a single leadership. It managed the presidency and key state apparatuses, shaped electoral rules, and used clientelism and corporatist bargaining to keep rivals within the system rather than let them win real power.

Elections under the PRI were consistently managed to maintain stability and continuity, often through coercive tactics, media influence, and control of local governments and the judiciary. This created a prolonged period where opposition parties faced significant barriers to competing on equal footing. By the late 20th century, economic crises and growing demands for democracy pressured the regime to open up, leading to reforms and credible opposition gains that culminated in the PRI losing the presidency in the 2000 election.

The other parties—PAN, PRD, and MORENA—emerged as challengers later, but none had the prolonged, systemwide dominance that the PRI enjoyed for decades.