New York State Route 173 (NY 173) is a state highway located in the Syracuse area of central New York in the United States. It takes a slightly bow-shaped route from NY 31 in the town of Van Buren to NY 5 in Chittenango, gently curving to the south of Downtown Syracuse in the center of its 30.59-mile (49.23 km) routing. Even so, NY 173 briefly enters the Syracuse city limits near where it intersects U.S. Route 11 (US 11). NY 173 passes through several suburbs of Syracuse, including Camillus, where it first meets NY 5, and Manlius, where it has a short overlap with NY 92.

New York State Route 31 (NY 31) is a state highway that extends for 208.74 miles (335.93 km) across western and central New York in the United States. The western terminus of the route is at an intersection with NY 104 in the city of Niagara Falls. Its eastern terminus is at a traffic circle with NY 26 in Vernon Center, a hamlet within the town of Vernon. Over its routing, NY 31 spans 10 counties and indirectly connects three major urban areas in Upstate New York: Buffalo–Niagara Falls, Rochester, and Syracuse. The route is one of the longest routes in New York State, paralleling two similarly lengthy routes, NY 104 to the north and NY 5 to the south, as well as the Erie Canal, as it proceeds east.