St. Mary's Church was founded on March 19, 1875, on the application of a number of members of St. Patrick's to Archbishop McCloskey, who granted an order dividing the original parish and constituting from the northern part of its territory St. Mary's parish. Rev. Michael J. Phelan was appointed pastor, and said his first mass in the parish on Easter Sunday, 1875, in the opera-house. The Wilson property at Gidney Avenue and South Street was purchased and mass celebrated in the mansion on the premises. In May following a temporary frame building for church purposes was erected. In 1880 the building occupied by the church until 2015 was erected. It was dedicated by Archbishop McCloskey on Sunday, October 3. The Academy of Our Lady of Mercy (a branch convent of the Sisters of Mercy of New York), which was opened at Balmville in the summer of 1875.