Question: what is the longest highway in the united states
Answer: U.S. Route 20; U.S. Route 20 in Nebraska; US 20; U.S. Route 20 in Ohio; US 20; U.S. Route 20 in Montana; US 20; U.S. Route 20 in Iowa; US 20; U.S. Route 20 in Massachusetts; US 20; U.S. Route 20 in New York; U.S. Route 20 in Oregon; U.S. Route 20 in Idaho; US-20; U.S. Route 20 in Indiana; U.S. Route 20 in Pennsylvania; US 20; U.S. Route 20 in Illinois; US 20