U.S. Route 31 is a major north-south highway in the United States, stretching approximately 1,000 miles from Mobile, Alabama to Mackinaw City, Michigan. It serves as an important connector for several states, facilitating travel and commerce along its route. The highway passes through various cities and towns, including Nashville, Tennessee and Indianapolis, Indiana. Established in the 1920s, U.S. Route 31 has undergone numerous improvements and realignments, making it a vital part of the U.S. highway system today.