The Parish of the Purification of the Blessed Virgin Mary (today St. Mary) began in 1858 when Fr. Peter Peters began celebrating Mass with a small group of Catholic families that settled in the coal-mining town of Trenton, Illinois. The people gathered for Mass in the home of Thomas McMahon and in the public school until a church was built in 1864 (with seating capacity of 200), at which time records of funerals and baptisms began to be kept. There was no resident pastor until Fr. Anthony Brefeld arrived in 1868. Before this time priests came from Highland, Aviston, and Breese.

The Catholic people built a small School in 1870 with Fr. Brefeld as the teacher; in 1876 some Sisters, Poor Handmaids of Jesus Christ, came to teach in the school.

   
The parish continued to grow in membership so that by 1883 the church had to be enlarged and by 1902 parishioners built a new larger school. The 155 families of the parish recognized their need to gather in addition to Sunday Mass and built themselves a Parish Hall in 1914.
 
Around this time parishioners were organizing themselves in various societies and sodalities. There was the St. Joseph Society for men, the St. Martha Society for women, the St. Aloysius Society for young men, the St. Agatha Sodality for young women, the Children of Mary and the Holy Guardian Angel Society.
 
As the Trenton community continued to grow, the Catholic Church grew also. By 1950, while Fr. Gerard Netemeyer was pastor, the parish had once again outgrown their church building and construction of a new one began. The new church was completed in 1953.. Parishioners numbered approximately 1500 by 1955.
 
St. Mary Catholic School had to be enlarged in 1961; enrollment the following year was 314. Six years later the operation of St. Mary School was taken over by the public school district. The district leased the building from the church, some Sisters continued as teachers and Religion was taught each morning before the school classes began.

Fr. Clement Dirler was appointed pastor in 1966 when the reforms of Vatican Council II renewed St. Mary Parish as it did the universal church. The life of the parish, especially the celebration of the Eucharist and other liturgies, became even more so the work of the laity along with the clergy. In 1975 one of St. Mary's parishioners, John Dilley, was ordained the first deacon in the diocese of Belleville and assisted with the leadership of the parish.
   
When Fr. Robert Flannery was appointed pastor in 1990, the people continued assuming greater responsibility for parish life through the establishment of Pastoral and Financial Councils and various committees. Because the number of priests was beginning to decline, the parish hired its first lay woman as Pastoral Associate in 1991. The elementary religion program, which was held daily, switched to a Sunday morning program. The sanctuary of the church was given a major face lift in 1998, with the conversion of the communion rail into a new ambo and baptismal font and the addition of the Emmaus Triptych. Fr. Jim Dougherty began serving the parish as pastor in 1999. Currently there are about 1600 parishioners from 600 families.