On January 6, 1875, two Sisters of Mercy from New Orleans arrived at Indianola. The superior, Mother Mary Camillus (Margaret) Lucas, and Sister Mary John Berchmans were later joined by four other sisters. Scarcely had their school been opened in September when a hurricane destroyed it and severely damaged the town. At the request of the pastor in Refugio, the sisters moved there in 1875 and established their first permanent convent. The school was made public in 1890; in 1916 the sisters established Mercy Academy, which became Our Lady of Refugio School in 1940. The sisters, under the direction of Sister M. de Pazzi (Mary Ann) Lucas, established a motherhouse and opened a day and boarding school. Mercy Hospital, later to become the motherhouse, was founded in Laredo in 1894. The sisters accepted teaching positions in public schools in Penitas, Roma, Mercedes, Mission, Edinburg, Point Isabel, and Rio Grande City. Some of these schools became parochial, as many of the buildings belonged to the Catholic Church. Mother Camillus and five sisters left Refugio to teach in the public school at San Patricio from 1876 to 1886. In 1887 they moved to Cuero, where a school and later a hospital were operated. Mother Camillus moved to Smithville in 1897 and opened a school that operated until her death in 1911; the two remaining sisters and a postulant moved to Lockhart to run St. Ignatius School, which had been discontinued by the Sisters of Divine Providence, who disbanded in 1913 and joined the Mercy sisters at Stanton.
The West Texas group of sisters arrived from San Francisco in 1894 and established an academy at Mariensfield (Stanton) and maintained it until a tornado demolished the buildings in 1938, after which they moved to join their sisters in Slaton. The Sisters of Mercy of the Southwest and West Texas joined with a number of other communities in America to form the Sisters of Mercy of the Union of the United States; they established their motherhouse in St. Louis, Missouri. These sisters continued to teach in Groom, Slaton, Edinburg, Harlingen, McAllen, Mercedes, Mission, Rio Grande City, and Refugio. They also owned hospitals in Slaton, Brownsville, and Laredo.
In 1990 the sisters continued to teach in diocesan and parish religious education at all levels. They did social work for the elderly, homeless, and refugees and attempted to alleviate poverty on both sides of the border. Several helped with the Laredo Regional Medical Center, a 334-bed hospital. The Pastoral Care Department had a staff of eight, including a deacon and two priests. Mercy also manages and staffs the Zapata Health Center and the South Texas Clinic. In 1994 there were twenty-one Sisters of Mercy in Texas and the South Texas Clinic. In 1994 there were twenty-one Sisters of Mercy in Texas.