
The BMT also used numbers to identify their routes, even going into double digits. For example, at the Wall Street station, the mosaics depict the old wall erected at the northern border of Dutch New Amsterdam, at Columbus Circle, you see mosaics of ships Christopher Columbus sailed on. The unique mosaics at each stop related to the history or landmarks of the ground above. These mosaics, notes New York City Transit Museum curator Jodi Shapiro, may have been a piece of wayfinding in the IRT system.

The design of the stations by architects Heins and Lafarge under the direction of chief engineer William Barclay Parsons incorporated elaborate ornamentation including intricate terra-cotta mosaics. The IRT used numbers to identify their lines, many of which have stayed the same to this day. Before the systems were merged, each had their own wayfinding and identification systems. Each of these systems operated independently of each other until 1940 when the city took over operations of all lines. The Independent Subway, the first city-owned system, opened in 1932. The Brooklyn-Manhattan Transit Cooperation came along in 1923 after acquiring the Brooklyn Rapid Transit Company (BRT). The first stop was the now-abandoned City Hall Station.

The Interborough Rapid Transit Company (IRT) was the first subway system to open in New York City in 1904.
