Interstate highways are a network of roads in the United States designed for long-distance travel and efficient transportation. Established by the Federal-Aid Highway Act of 1956, these highways connect major cities and regions, facilitating commerce and travel across the country. They are characterized by multiple lanes, limited access points, and high speed limits. The Interstate System consists of over 47,000 miles of roadways, making it one of the largest highway systems in the world. These highways are crucial for emergency services, military transport, and everyday commuting, significantly contributing to the nation's economy and mobility.