The term 'National Highway' is often used interchangeably with the term 'INTERSTATE, ' which is a 10-letter word. The National Highway System is a network of highways that are owned and maintained by the federal government in the United States. It was established in 1956 and consists of over 160, 000 miles of roads. The system includes the INTERSTATE Highway System, which is a network of freeways that connect major cities across the country. The National Highway System also includes other roads such as rural highways, scenic byways, and toll roads.