The Partido Liberal Mexicano, the major political organization of Mexican and Mexican-American intellectuals who supported the Mexican Revolution, operated in Texas during the first two decades of the twentieth century. It called for the overthrow of Mexican president and dictator Porfirio Díaz. PLM was organized at the Congreso Liberal, which first met at the Teatro de Paz in San Luis Potosí, Mexico, for eight days beginning on February 5, 1901, to discuss the Díaz regime's departure from the Mexican Constitution of 1857, especially its anticlerical provisions. Camilo Arraiga's manifesto of August 30, 1900, "Invitación al Partido Liberal," resulted in the formation of fifty affiliate clubs within the five months leading to the gathering. Arraiga, an heir to his family's silver-mining wealth, represented the elite, who wanted to reform the government, while Ricardo Flores Magón, who also attended the meeting and became the leading proponent of PLM, represented the intellectuals who had risen from the working class and who eventually called for complete revolution and the ouster of Díaz. The first hint of this latter action occurred at the congress when Flores Magón addressed the audience, urging the liberals to renounce the Díaz administration. A few months after the meeting, Flores Magón published a demand to end Díaz's regime in Regeneración, a magazine he had started as a law student, which became the PLM newspaper. He was promptly arrested and imprisoned for a year without a trial. Within two years after the Congreso Liberal, PLM reorganized and issued a new manifesto that went beyond a mere desire for reform. It expressed a concern for the working class and peasants and issued an ultimatum for ending the suppression of free speech and the concentration of wealth in a small clique. After several other arrests and imprisonments in Mexican jails, Flores Magón and his brother Enrique fled to Laredo, Texas, where they arrived on January 3, 1904.
With the arrival of the Flores brothers in Texas, PLM set up its first headquarters in exile in the United States. The party was able to establish itself in Laredo with the assistance of Texas Mexicans. Poet and labor activist Sara Estela Ramírez offered her home as the organization's first headquarters. Ramírez, a PLM supporter since its founding in Mexico, also helped coordinate its work and became one of Flores Magón's most important contacts in the state. In an effort to shield itself from Mexican government harassment, PLM soon moved its headquarters to San Antonio, reestablished Regeneración there in November 1904, and garnered more local support as the party became better known. Although a late-night raid on its San Antonio offices forced PLM to move once again, this time to St. Louis, Missouri, it nonetheless continued to receive the support of many Texas Mexicans who wanted to end an oppressive social order. PLM activity was prominent in Del Rio, an important center for prerevolutionary activity, in San Antonio, and especially in El Paso, where the location just across the border from Mexico provided a fortress for Mexican dissidents once the revolution began. In Cameron and Hidalgo counties, 165 Floresmagonista clubs ultimately were formed. On the American side of the border, PLM helped form the attitudes that led to the Plan of San Diego of 1915, a scheme that called for the violent overthrow of Caucasian dominance in South Texas.
PLM advanced anti-Díaz sentiment through newspapers, chief among them Regeneración, and through political pronouncements on the ideals espoused by Flores Magón, one of whose best-known statements on PLM ideology, "A la mujer" ("To Women"), appeared in the September 24, 1910, edition of Regeneración. In the document Flores acknowledged the economic inequity women suffered and called on them to stand together with men against the Díaz tyranny. Many women took up the PLM cause. Besides Sarah Ramírez and Andrea and Teresa Villarreal, publishers of La Mujer Moderna, Isidra T. de Cárdenas, Flores de Andrade, Teresa Urrea, and many anonymous women established revolutionary newspapers and organized women's groups to support anti-Díaz activities.
PLM also smuggled arms across the border to revolutionary forces in Northern Mexico, and some clubs, the Del Rio group for instance, launched raids into Mexico, particularly after PLM issued its updated revolutionary program in July 1906. The attacks, which violated American neutrality laws, drew the scrutiny of both Mexican and United States officials. Ultimately, the two governments cooperated in suppressing PLM. Mexico hired the Burns and Sheridan National Detective Agency of New York City to track revolutionary activities in Texas and Mexico, and the United States Department of Justice assisted Mexican officials by posting special officers in Texas and establishing new deputy positions to enforce neutrality laws through the United States marshall's office in San Antonio. Mexico also enlisted its consuls along the border in surveillance activities, including the interception of PLM mail traveling across the border. Consular measures against PLM were met with hostility by many Texas Mexicans. Nevertheless, they successfully prevented the revoltosos ("unruly ones," the revolutionaries in the United States) from publishing their newspapers and assisted in the arrest and deportation of PLM activists. The United States consul appointed Luther T. Ellsworth to serve in the Ciudad Porfirio Díaz office, across the river from Eagle Pass, to gather intelligence reports on the Floresmagonistas. Though the activities of the revoltosos leveled off in 1917, government suppression of PLM continued until around 1923, the year after Flores Magón died in the United States federal penitentiary at Fort Leavenworth, Kansas. In the 1960s and early 1970s the Chicano movement revived the PLM spirit of resistance and political activism.