'Se Cayó el Sistema' — 1988 Election: PRI vs. Cárdenas Coalition

The July 6, 1988 presidential election pitted PRI candidate Carlos Salinas de Gortari against Cuauhtémoc Cárdenas Solórzano, leading a broad center-left coalition (FDN). On election night, the government's computer system (PREP predecessor) 'crashed' when early unofficial counts showed Cárdenas winning. When results were announced, Salinas had won with 50.7%. International observers found the election marred by fraud; ballot boxes were subsequently incinerated by a PRI-controlled Congress. The 1988 crisis made electoral reform Mexico's central political demand of the 1990s.