A snowplow (also snow plow, snowplough or snow plough) is a device intended for mounting on a vehicle, used for removing snow and ice from outdoor surfaces, typically those serving transportation purposes. Although this term is often used to refer to vehicles mounting such devices, more accurately they are known as winter service vehicles, especially in areas that regularly receive large amounts of snow every year, or in specific environments such as airfields. In other cases, pickup trucks and front end loaders are outfitted with attachments to fulfill this purpose. Some regions that do not frequently see snow may use graders to remove compacted snow and ice off the streets. Snowplows can also be mounted on rail cars or locomotives to clear railway tracks. Usage A snowplow works by using a blade to push snow to the side to clear it from a surface. Modern plows may include technology to make it easier to perform the work and stay on the road. These include Global Positioning System receivers, head-up displays and infrared cameras. Large custom snowplows are commonly used at major airports in North America. These plows have oversized blades and additional equipment like a rotating sweeper broom (sometimes called jetblade) and blowers at the rear of the plow. For sidewalks and narrow lanes small tractor plows (tracked or wheeled) are often used within Canada and the United States. When snowfall accumulates above a certain height, snowplow operators may be seen clearing the main arteries first (designated as snow routes), in some cases for the exclusive use of emergency vehicles. Underbody scrapers are sometimes mounted on vehicles in residential and urban settings, operating on principles similar to a road grader, but allowing greater weights and speed along with the carriage of a road treatment applicator. Newer technology has allowed the use of articulated plow systems which can clear multiple divided highway lanes simultaneously; jurisdictions adopting this technology include the provinces of Alberta, British Columbia, New Brunswick, Ontario and Quebec in Canada, along with 21 states (Colorado, Connecticut, Delaware, Indiana, Kansas, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Montana, New Hampshire, New York, North Dakota, Ohio, Oregon, Pennsylvania, Tennessee, Utah and Wisconsin) in the US. History The first snow plows were horse-drawn wedge-plows made of wood. The earliest reference found by the Oxford English Dictionary was written in 1792 in a description of New Hampshire: With the advent of rail travel and