The Presbyterian Church in the U.S. Mexico Mission traces its origins to the early 1870s, when the Executive Committee of Foreign Missions sent Rev. Anthony Thomas Graybill and Rev. John W. Neil to survey Brownsville and eastern Mexico for mission work. In 1873, A.T. Graybill and his wife, Douglass Taylor Graybill, were appointed as missionaries and they settled in Matamoros in 1874.  Over the next three decades, the PCUS mission presence slowly grew, as the missionaries established churches and schools throughout Nuevo Leon and Tamaulipas, and prepared Mexican ministers for ordination.

Beginning with A.T. Graybill’s training of Leandro Garza Mora, the first Mexican ordained as a Presbyterian minister, PCUS missionaries supported the development of a National Presbyterian Church and the Mexican clergy. In 1884, the Presbytery of Tamaulipas was organized in Matamoros, with Garza as its first Moderator. In 1901, the Presbytery of Tamaulipas joined with the three presbyteries connected to the Presbyterian Church in the U.S.A. Mexico Mission to form the Iglesia Nacional Presbiteriana de México (National Presbyterian Church of Mexico). A national synod was organized in 1904, and the General Assembly of the National Church was formed in 1947.

The Mexican Revolution, which began in late 1910, did not immediately affect the work of the mission, but as the fighting moved into the northeast, missionaries were forced to return to the U.S., making only sporadic trips back to visit churches and schools. In the summer of 1914, the Committee on Cooperation in Latin America called a meeting in Cincinnati of the eleven American Protestant mission boards working in Mexico to reallocate mission territories and to discuss the establishment of a union seminary at Coyoacán, and a union press. Under the “Cincinnati Plan,” the PCUS mission was slated to move from the northeast to the south-central region of Mexico. The new field included the states of Guerrero and Michoacán, and part of the states of Mexico and Morelos, territory formerly occupied by Methodist and Presbyterian Church in the U.S.A. missions. The mission’s move was made official at the 1919 meeting of the Presbytery of Tamaulipas, and was completed in 1920.

The mission’s work in the south was initially centered in Toluca, capital of the state of Mexico, and Zitácuaro in Michoacán. The Graybill Memorial School, originally established in Montemorelos in 1911 to train boys in agriculture and industry, was transferred to Zitácuaro, which was also the site of a girls’ primary school, La Centenarista. In 1922, the mission opened Sanatorio La Luz, a hospital and nursing school in Morelia. Within just a few years of the hospital’s opening, it became impossible for foreign doctors to receive licenses to practice in the country, so Mexican medical staff took over the work. A second hospital, Sanatorio La Amistad, was opened in 1958 in Ometepec, Guerrero.

The PCUS mission fostered the formation, in 1921, of the Presbytery of the South (Presbiterio del Sur), with six Mexican ministers as members. In 1936, the presbytery was divided, with churches in the states of Mexico and Michoacán continuing under the Presbytery of the South, and churches in Guerrero and Morelos under the new Presbytery of the Pacific (Presbiterio del Pacifico).

The Mexican Constitution of 1917 and the enactment of legislation during the 1930s limited Protestant influence in such areas as ordination of ministers, education and the ownership of property. Though private worship was not to be interfered with, public worship was only to be held in church buildings specifically recognized by the State. Despite these restrictions, the mission continued to minister to the educational and evangelistic needs of the Mexican people.

Missionaries taught at the union seminary at Coyoacán, presbytery-run Bible schools, and secular schools, including the Instituto Juarez in Mexico City, Cuernavaca, and Morelia. The mission also operated or supported Christian boarding hostels for boys and girls, known as internados.  Missionaries engaged in itineration (some of which was accomplished by airplane), agricultural extension work, literature distribution, and audio-visual evangelization. The mission conducted much of its work in conjunction with the National Church and supported the organization of women’s work through the synodical and presbyterial unions of the National Church.