Bishop Canevin presided at the solemn dedication of third church building for Saint Mary, Help of Christians Parish on Sunday, May 28, 1905. The seating capacity was counted at 1,400. A number of Italian immigrants had settled in McKees Rocks and the adjoining Stowe Township. They found their way to the closest Italian parish, Saint Peter, on Fernando Street in Pittsburgh’s Hill District. Under the pastoral care of the Franciscan Friars, these faithful men and women eventually began to lobby support from other Italians to collect the funds necessary to build a church of their own.
These immigrants received a warm welcome from Father Tonner, who offered them the basement church at Saint Mary for baptisms, weddings and funerals. Four lots in Stowe Township were eventually purchased, and in November 1906, Father Tonner laid the cornerstone for the new church. The men who were leaders in the new parish requested to name the parish in honor of the Blessed Virgin Mary. By 1907, Mother of Sorrows Parish was moving forward with its own pastor, Father Vincent Diaferia.
During that same time the immigrants from Slovakia formed the fifth parish in the McKees Rocks area, establishing Saint Mark Parish in October 1906, when Bishop Canevin assigned a pastor, Father Andrew Pohorenec. Ten lots were purchased on Munson Avenue early in 1907, and by 1910 construction of the church foundation, basement and rectory was completed.
The history of Holy Trinity Parish begins after Catholics who resided in Moon Run sought permission to establish a parish there in 1906. Because there was not a sufficient amount of people to form a new parish at that time, a church that was designated as a mission of Saint Columbkille, Imperial, was erected instead. The first Mass was celebrated in the basement of the mission church in August 1908, and that first church building was dedicated in May 1909. That same year, a new grade school was built at Saint Francis de Sales, and the old church was converted into a high school.