[4] As part of the Dual Contracts, two lines under Flatbush Avenue, one each operated by the BRT and IRT, were approved.

The Cranford Company received a construction contract for this section in March 1914 after making a low bid of about $2.2 million.

[10] Service on the IRT Eastern Parkway Line had been extended from Atlantic Avenue to Utica Avenue in August 1920,[11] but the Bergen Street, Grand Army Plaza, and Eastern Parkway–Brooklyn Museum stations were not ready to open with the rest of the line.

[18] During the 1964–1965 fiscal year, the platforms at Grand Army Plaza, along with those at four other stations on the Eastern Parkway Line, were lengthened to 525 feet (160 m) to accommodate a ten-car train of 51 foot (16 m) IRT cars.

[20] In April 1993, the New York State Legislature agreed to give the MTA $9.6 billion for capital improvements.

Some of the funds would be used to renovate nearly one hundred New York City Subway stations,[21][22] including Grand Army Plaza.

[32] The bronze and terra cotta pieces of art are modeled on the original Interborough Rapid Transit Company logo, and alludes to the Soldiers' and Sailors' Arch in the plaza above with its Winged Victories.