U.S. Route 20A (US 20A) is an east–west alternate route of US 20 that extends for 83.59 miles (134.53 km) across the western portion of New York in the United States. It leaves US 20 in Hamburg, a suburb of Buffalo, and rejoins it in East Bloomfield about five miles (8.0 km) west of Canandaigua, the county seat of Ontario County. The western terminus is situated just northeast of the intersection of US 20 and US 62 and west of Highmark Stadium. At its east end, US 20A also meets New York State Route 5 (NY 5) and NY 64. Most of the route is known as Big Tree Road; outside Highmark Stadium, the highway is known as the Timothy J. Russert Highway in memory of Buffalo native Tim Russert.

U.S. Route 20 (US 20) is a part of the United States Numbered Highway System that runs from Newport, Oregon, to Boston, Massachusetts. In the U.S. state of New York, US 20 extends 372.32 miles (599.19 km) from the Pennsylvania state line at Ripley to the Massachusetts state line in the Berkshires. US 20 is the longest surface road in New York. It runs near the Lake Erie shore from Ripley to Buffalo and passes through the southern suburbs of Buffalo, the Finger Lakes, the glacial moraines of Central New York, and the city of Albany before crossing into Massachusetts. US 20 connects to all three major north–south Interstate Highways in Upstate New York: Interstate 390 (I-390) near Avon, I-81 south of Syracuse, and I-87 in Albany by way of NY 910F.