St. Mary's (of the Assumption) Parish in Bridgeton, Missouri was a Catholic parish located in the Archdiocese of St. Louis. The parish was founded in 1851 and closed in 2001. It was founded by Jesuit priests from St. Ferdinand Parish in Florissant, Missouri. The parish's grade school, St. Mary's School, existed from 1886 until 1999. The church and school were located on the southwest corner of the Natural Bridge Road and Long Road intersection. The church, school, convent, and rectory were razed in 2004 to make way for the Lambert-St. Louis Airport expansion. The Jesuits(SJ) ran the parish from its origin through the erection of the new church, school, and rectory that were built in 1954 with the leadership of pastor Fr. J.T. Morrell, SJ. The new school included 14 classrooms, a faculty lounge, a cafeteria, band loft above the church, and a lounge under the church. The church was attached to the school because church was meant to be the school's gymnasium. The new church in the parish masterplan was never built due to a lack of funds. The Sisters of St. Joseph of Carondelet (CSJ) operated and taught in the grade school until 1987 and also directed St. Mary's High School. The high school existed from 1944-1956. The parish's new families in the 1950s and 1960s multiplied so much that the Archdiocese of St. Louis had to redraw parish boundaries seven times and open seven new parishes to serve the needs of the deanery. At one point in the late 1960s, the enrolment at St. Mary's topped 720 students.
Most graduates of St. Mary's School attended high school at St. Thomas Aquinas in Florissant which later became St. Thomas Aquinas-Mercy after merging with Mercy High School in University City in September 1985. Many girls were accepted to Incarnate Word Academy in Normandy, Missouri, and boys were accepted to Christian Brothers College in Clayton, De Smet Jesuit High School in Creve Coeur, and St. Louis University High in the City of St. Louis. Public schools included Pattonville Senior High School and Ritenour Senior High School.
The following parishes were formed from families of St. Mary's Parish. When the parish was closed, many St. Mary's families moved to these parishes.
After the closure of St. Mary's, parishioners joined the parishes listed above that formed out of St. Mary's. Due to a declining number of Catholics in the northwest deanery and airport expansion, several parishes have combined.
In 2003, St. Gregory, St. Kevin, and St. Williams merged. The new parish is called Holy Trinity. Holy Trinity's church, parish center, rectory, convent, and youth center is located at the former St. Gregory Parish on St. Luke Lane and the school is located at the former St. Kevin Parish on St. Henry Lane.
In 2004, St. Lawrence the Martyr was purchased as part of the St. Louis-Lambert Airport expansion as well. St. Lawrence the Martyr merged with St. Blaise to form Holy Spirit Parish in 2004. Holy Spirit is located at the former St. Blaise Parish on Parkwood Lane in Maryland Heights. The same week that St. Lawrence and St. Blaise merged, Our Lady of Mercy in Hazelwood closed and members joined St. Martin de Poerres in Hazelwood.
St. Jude remains in operation.