The original Westchester school building was completed for the opening of the 1956-57 school year with a starting enrollment of 149 students. Currently, Westchester has an enrollment of approximately 520 students from seven local municipalities. The school is located in Kirkwood, Missouri, a St. Louis County suburb, on approximately 10 acres and includes a wooded wildlife area on the east boundary. This area is referred as "The Westchester Woods." It includes a low ropes course, and outdoor learning center that is used by teachers and students. The original building structure is now the south wing and cafeteria area of the present building. Additions were completed in 1958 (north wing) and in 1964 (east wing). In 1993, a second gymnasium was added and other renovations resulting from a bond issue including air-conditioning, technology infrastructure, and interior upgrades.
In 2005, the community approved Proposition I, a two-part bond initiative that provided funds for improvements and infrastructure repairs throughout the district as well as funds to complete the district’s master facilities plan. Prop I improvements at Westchester included new domestic/fire main, new fire alarm, tuck pointing, storm line repairs, north gym walls painted, and asphalt sealing.
Westchester celebrated its 50th anniversary in 2007. In the summer of 2013, the Westchester office was relocated to the front of the building to increase safety and security for our students and staff.
In 2017, extensive renovations were completed in the Westchester Woods. These renovations were funded by donations from parents and the community and included adding an ampitheater, a Whale Watch ropes course element, a Naturescape area, reading benches, a Monarch Weigh Station and the reintroduction of native plants and trees. In addition to these enhancements, a Community Library was added to each of the playground areas and a Gaga Ball pit was added to the north playground. Finally, an under-utilized shed was renovated on the south playground and transformed in to a chicken coop where 13 chickens live and entertain students, staff, and members of the community. In early 2018, an indoor bee hive was added to the main foyer.