The expansion of the population of the County of New York (Manhattan) northward into the neighboring Borough of the Bronx, Westchester County and the shipping dangers on the Harlem River, the northern boundary for Manhattan, and a vital connection for the East River to the Hudson River, encouraged the physical connection of Manhattan Island to the Bronx. Several bridges had been built, one being the High Bridge (also known as Harlem River Bridge) built by John B. Jervis to carry the Croton Aqueduct (1836-46) water from upstate New York across the Harlem River into Manhattan (also served as a pedestrian walkway). In the vicinity of Third Avenue, Manhattan, a previous bridge had been built by John B. Coles and Lewis Morris by a franchise conferred by the N.Y. State Legislature Acts of March 31, 1790, March 30, 1797, and April 3, 1798. This bridge was a stone dam type bridge across the Harlem River with a navigation lock in it to allow ship passage. It became known as the Coles Bridge and its lucrative tolls made it be incorporated in 1808 by Coles and Morris as the Harlem Bridge Company with a charter of 60 years. The well-maintained span was the principal artery of travel to Connecticut and Boston and the area prospered. The owners tried to extend the charter but the State Legislature, noting that the bridge was not strong enough to carry the heavy railroad traffic, empowered the counties of New York and Westchester to build a new capacious bridge. This next Third Avenue bridge was the first iron bridge built in New York. It is the building of this bridge that the Copy of Engineers Private Journal Harlem Bridge journal describes.
From the description of Copy of engineers private journal [on] Harlem Bridge 1857-1861. 1857-1861. (Lehigh University Libraries). WorldCat record id: 319715134
