A highway is any public road or other public way on land; the term exists in distinction to waterway. In North American and Australian English, the term frequently implies major roads under the control of a state or provincial agency instead of a local road authority. In British English, highway is primarily a legal term, and normal usage implies roads, while legal usage covers any route or path with a public right of access, including footpaths etc. The term has led to several related derived terms, including highway system, highway code, and highway patrol.
Major highways are often named and numbered by the governments that typically develop and maintain them. Australia’s Highway 1 is the longest national highway in the world at over 14,500 km (9,000 mi) and runs almost the entire way around the continent. 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. Some major highway routes include ferry services, such as U.S. Route 10, which crosses Lake Michigan.
Traditionally highways were used by people on foot or on horses. Later they also accommodated carriages, bicycles and eventually motor cars, facilitated by advancements in road construction. In the 1920s and 1930s, many nations began investing heavily in progressively more modern highway systems to spur commerce and bolster national defense.