 It was the second alternate route of US 20 near Syracuse; the first, NY 20N, was also a northern alternate route of US 20 but it followed a more southerly routing than NY 20SY.Most of NY 20SY was concurrent to other, pre-existing state highways in the Syracuse area, namely NY 321, NY 5, NY 92, NY 173, and NY 20N.NY 5 was assigned in 1924; NY 92, NY 173, and NY 321 were assigned as part of the 1930 renumbering of state highways in New York; and NY 20N was assigned .