This station was built as part of the Pelham Line, which was part of the
Dual Contracts, signed on March 19, 1913, and also known as the Dual Subway System. The Pelham Line was proposed to be a branch of the
Lexington Avenue Line running northeast via
138th Street, Southern Boulevard and Westchester Avenue to Pelham Bay Park. This station opened on October 24, 1920 as the line's new terminal with the line's extension from
East 177th Street. Service was initially served by a mix of through and shuttle trains during the 1920s. In 1981, the
Metropolitan Transportation Authority (MTA) listed the station among the 69 most deteriorated stations in the subway system. Under the 2015–2019 MTA Capital Program, the station, along with thirty other New York City Subway stations, was to undergo a complete overhaul and would have been entirely closed for up to six months. Updates would have included cellular service, Wi-Fi, charging stations, improved signage, and improved station lighting. However, these renovations were deferred due to a lack of funding. Regardless, the station was closed in one direction for approximately two months (one month per direction) to facilitate
ADA accessibility renovations. As part of a revision to the Capital Program in April 2018, the MTA announced that the station would have elevators installed, making the station ADA-accessible. By February 2021, funding had been committed to accessibility renovations at the station. In December 2021, the MTA awarded a contract for the installation of elevators at eight stations, including the Westchester Square station. The project, which also included structural repairs and restoration of historic features, cost $122.5 million, of which $98.6 million was funded by the
Federal Transit Administration. In addition, four new stairways were added, eight stairways were renovated, and new fire alarm and communication systems, and
CCTV cameras were installed. , the project was scheduled to be completed in May 2024, but the elevators did not open until January 2025. == Station layout ==