Third Ave. at 166th St., looking north. Shoring used in reconstruction of Third Ave, 1914.

The Third Avenue elevated line was original constructed in 1875-1878 by the New York Elevated Railway Company. The line traveled from South Ferry at the lower tip of Manhattan to 129th Street at the northern tip. The extension over the Harlem River came in 1886, with the construction of more northern Bronx stations between 1887 and 1920, when it reached its final terminus at Gun Hill Road.

The railway line was merged and bought out a number of times before 1905. Manhattan Railway took over control of the New York Elevated Railroad in 1879. In 1891 they also took over the Suburban Rapid Transit Company, which operated the line that crossed the swing bridge over the Harlem River. In 1902 it all became a part of the Interborough Rapid Transit Company, when Manhattan Railway leased the line for a period of 999 years! It was at this time the line was also electrified.

In the 1910s, as part of the Dual Contracts that constructed a number of new subway lines, the Third Avenue line was triple-tracked (the work for that is depicted in this image). The third (center) track in the Bronx opened in 1916. The Third Avenue line in the Bronx outlived part of the elevated line that traveled through Manhattan. The Bronx section closed and was demolished in 1973.