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State highway, state road or state route (and the equivalent provincial highway, provincial road or provincial route) can refer to one of three related concepts, two of them related to a state or provincial government in a country that is divided into states (including the Australia, India, Mexico, and the United States) or provinces (including Canada and China):
- A road numbered by the state or province, falling below numbered national highways in the hierarchy. Route numbers are used to aid navigation, and may or may not indicate ownership or maintenance.
- A road maintained by the state or province, including nationally-numbered highways and un-numbered state highways
Depending on the state, state highway may be used for one meaning and state road or state route for the other. A third meaning, used in some countries such as New Zealand, uses the word "state" in its sense of a nation. By this meaning a state highway is a road maintained and numbered by the national government rather than local authorities.
The usage of the terms "state highway", "state route", etc. may vary from country to country or even from state to state.
National usage 
Australia's State Route System is a system of urban and inter-regional routes that are not covered by the National Route System, or the National Highway System. These routes are marked with a blue shield. Sometimes a state route may be formed when a former national route is decommissioned.
Brazil is another country that is divided into States and has state highways.
Canada is divided into provinces and as such has Provincial Highways.
Italy's Strade Statali extend for some 12,000 km, overseen by the Azienda Nazionale Autonoma delle Strade (ANAS) founded in 1946, replacing the A.A.S.S. (Azienda Autonoma delle Strade Statali) of 1928.
Mexico's State Highway System is a system of urban and state routes constructed and maintained by each Mexican State. The main purpose of the state networks is to serve as a feeder system to the federal highway system. All states except the Federal District operate a road network. Each state marks these routes with a white shield containing the abbreviated name of the state plus the route number.
New Zealand 
New Zealand's state highway system is a nationwide network of roads covering the North Island and the South Island. As of 2006, just under 100 roads have a "State Highway" designation. The New Zealand Transport Agency administers them. The speed limit for most State Highways is 100 km/h, with reductions when a State Highway passes through a densely-populated area.
The highways in New Zealand were originally designated on a two-tier system, National (SH 1–8) and Provincial, with national highways having a higher standard and funding priorities. Now all of them are State Highways, and the network consists of SH 1 running the length of both main islands, SH 2–5 and 10–58 in the North Island, and SH 6–8 and 60–99 in the South Island. National and Provincial highways are numbered approximately North to South. State Highway 1 runs the length of both islands.
United States 
State highways are generally a mixture of primary and secondary roads, although some are freeways (for example, State Route 99 in California, which links many of the cities of the Central Valley, Route 128 in Massachusetts, Ronald Reagan/Cross County Highway (State Route 126) in Cincinnati, or parts of Route 101 in New Hampshire). Each state has its own system for numbering and its own marker. The default marker is a white circle containing a black sans serif number (often inscribed in a black square or slightly rounded square), according to the Manual on Uniform Traffic Control Devices (MUTCD). However each state is free to choose a different marker, and most states have. States may choose a design theme relevant to its state to distinguish state route markers from interstate, county, or municipal route markers.
See also 
- List of Canadian highways by province
- List of longest state highways in the United States
- List of state highways in the United States shorter than one mile
- List of numbered highways in the United States
- Interstate Highway System, U.S. Highway System
- Missouri Supplemental Route
- County highway
- Highways in Australia
- New Zealand State Highway network
- Numbered street