A highway is a public road, especially a more major road connecting two or more destinations. Traditionally highways were used by people on foot or on horses, then carriages and more recently by motor cars. Major modern highways in industrialized countries typically have two or more lanes on each carriageway, have dual carriageways (divided highway), limited access and have grade-separated junctions. Any interconnected set of highways can be variously referred to as a "highway system", a "highway network", or a "highway transportation system".[1] Each country has its own national highway system.
The United States has the world's largest network of highways, including both the Interstate Highway System and the U.S. Highway System. At least one of these networks is present in every state and they interconnect most major cities. Some highways, like the Pan-American Highway or the European routes, span multiple countries. Australia's Highway 1 is the longest national highway in the world at over 14,500 kms (9,000 miles) and runs almost the entire way around the continent. Some major routes include ferry services, including U.S. Route 10, which crosses Lake Michigan.