High Quality Content by WIKIPEDIA articles! U.S. Route 15 (US 15) is a part of the U.S. Highway System that runs from Walterboro, South Carolina, to Painted Post, New York. In the U.S. state of New York, US 15 extends 12.68 miles (20.41 km) through the Southern Tier from the Pennsylvania state line at Lindley north to an interchange with the Southern Tier Expressway (Interstate 86 or I-86 and New York State Route 17 or NY 17) just outside of Painted Post. US 15 originally continued north to Rochester before being truncated to its present northern terminus. All of US 15 in New York will eventually become part of I-99, an Interstate Highway that currently only exists in central Pennsylvania.