Because of its designation as the widest avenue on Manhattan's East Side, Park Avenue originally carried the tracks of the New York and Harlem Railroad built in the 1830s, just a few years after the adoption of the Manhattan street grid.

Although the name “Park Avenue” was first used for part of Fourth Avenue around 1860, it was not until 1888 that a section of the street was officially renamed. The new name, while describing the improvements made to the street, was largely a marketing move.

noun. a wide street in New York City traditionally associated with luxurious residential and professional buildings, fashionable living, and high society.

Park Avenue's entire length was formerly called Fourth Avenue; the title still applies to the section between the Bowery and 14th Street. The avenue is called Union Square East between 14th and 17th Streets, and Park Avenue South between 17th and 32nd Streets.