Guadalajara and Jalisco in general were the center of the Cristero Wars (1926-1929), a rebellion by catholic guerillas against the secularizing reforms of Plutarco Calles's presidency. One of the first armed conflicts of the rebellion took place in Gudalajara in the Church of Our Lady of Guadalupe (August 3, 1926), where a group of several hundred cristeros engaged in a shootout with federal troops. Guadalajara itself was attacked (unsuccessfully) by the Cristero armies in March of 1929.

In the 1950s Av Juárez was widened to create the arterial axis of Juárez-Vallarta which you see today. A famous part of that work was moving the central telephone exchange without disrupting service. Pictures of this feat of engineering can be seen in the City Museum.

In April 1992, the Reforma area was rocked by a huge explosion of gasoline, when a gasoline pipe line leaked into the sewers over a period of days until the fumes finally detonated. Some 200 were killed and several thousand injured. The explosion affected mostly the working class and industrial sector on the South side of the city.