Parking is the act of stopping a vehicle and leaving it unoccupied for more than a brief time. It is against the law virtually everywhere to park a vehicle in the middle of a highway or road; parking on one or both sides of a road, however, is commonly permitted. Parking facilities are constructed in combination with most buildings, to facilitate the coming and going of the buildings' users.
Parking facilities include indoor and outdoor private property belonging to a house, the side of the road where metered or laid-out for such use, a parking lot or car park, indoor and outdoor multi-level structures, shared underground parking facilities, and facilities for particular modes of vehicle such as dedicated structures for cycle parking.
In the U.S., after the first public parking garage for motor vehicles was opened in Boston, May 24, 1898, livery stables in urban centers began to be converted into garages. In cities of the Eastern US, many former livery stables, with lifts for carriages, continue to operate as garages today.
The following terms give regional variations. All except carport refer to outdoor multi-level parking facilities. In some regional dialects, some of these phrases refer also to indoor or single-level facilities.
Besides these basic modes of motor vehicle parking, there are instances where a more ad hoc approach to arranging motor vehicles is appropriate. For example, in parts of some large cities, such as Chicago, where land is expensive and therefore parking space is at a premium, there are parking lots for motor vehicles where the driver leaves the keys to the vehicle with an attendant who arranges vehicles so as to maximize the number of vehicles that can be parked in the lot. Vehicles may be packed up to five vehicles deep in combinations of perpendicular and/or parallel parking with limited circulation aisles for the parking attendant. Such arrangements are known as attendant parking. When the lot or facility is provided to serve the customers of a business, it is considered valet parking.
Inner city parking lots are often temporary, the operators renting land which is vacant pending the construction of a new office building. Some inner city lots are equipped with individual lifts, allowing cars to be stored above each other.
Another ad hoc arrangement is tandem parking. This is sometimes done with residential motor vehicle parking where two motor vehicles park nose-to-end in tandem. The first motor vehicle does not have independent access, and the second motor vehicle must move to provide access. As with attendant parking, the purpose is to maximize the number of motor vehicles that can park in a limited space.
With parallel parking of cars, these are arranged in a line, with the front bumper of one car facing the back bumper of an adjacent one. This is done parallel to a curb, when one is provided. Parallel parking is the most common mode of streetside parking for cars. It may also be used in parking lots and parking structures, but usually only to supplement parking spaces that use the other modes.
Often, in car parking lots using perpedicular parking, two rows of parking spaces may be arranged front to front, with aisles in between.
Sometimes, a single row of perpendicular car parking spaces is marked in the center of a street. This arrangement eliminates reversing from the maneouver; cars are required to drive in forwards and drive out forwards.
Angle parking is very common in car parking lots. It may also be used in streetside car parking when there is more width available for car parking than would be needed for parallel parking of cars, as it creates a larger number of parking spaces. Some cities have utilized angled parking on-street (as compared to off-street parking facilities). This has been done mostly in residential, retail and mixed use areas where additional parking compared to parallel parking is desired and traffic volumes are lower. Most angled parking is design in a head-in configuration while a few cities (Seattle and Portland are examples) have some back-in angled parking (typically on hills or low traffic volume streets).
In congested urban areas parking of motor vehicles is time consuming and sometimes expensive. Urban planners must consider whether and how to accommodate or 'demand manage' potentially large numbers of motor vehicles in small geographic areas. Usually the authorities set minimum, or more rarely maximum, numbers of motor vehicle parking spaces for new housing and commercial developments, and may also plan its location and distribution to influence its convenience and accessibility. The costs or subsidies of such parking accommodations can become a heated point in local politics. For example, in 2006 the San Francisco Board of Supervisors considered a controversial zoning plan to limit the number of motor vehicle parking spaces available in new residential developments.
In the graph to the right the value above the line represents the out-of-pocket cost per trip, per person for each mode of transportation, the value below the line accounts for subsidies, environmental impact, social and indirect costs. When cities charge market rates for on street parking and municipal parking garages for motor vehicles, and when bridges and tunnels are tolled for these modes, driving becomes less competitive in terms of out-of-pocket costs than other modes of transportation. When municipal motor vehicle parking is underpriced and roads are not tolled, the shortfall in tax expenditures by drivers, through gas tax and other taxes amounts to a very large subsidy for automobile use. The size of this subsidy for cars dwarfs the federal, state, and local subsidies for the maintenance of infrastructure and discounted fares for public transportation.
Where car parking spaces are a scarce commodity, and owners have not made suitable arrangements for their own parking, ad hoc overspill parking often takes place along sections of road where there is no planned scheme by a municipal authority to formally allocate roadspace to the car. Heated social discourse sometimes revolves around the sense of "ownership" that informally arises amongst individuals displaying overspill parking behaviour. For example, during the winter of 2005 in Boston, the practice of some people saving convenient overspill roadway for themselves, became controversial. At that time, many Boston regions had a tradition that if a person shoveled the snow out of a roadspace, that person could claim ownership of that space with some kind of marker (e.g. a chair or orange cone) in the space. However, city government defied that custom and cleared markers out of spaces. Indeed, parking space in Boston is such a rare commodity that in 2006 a single parking space sold for $250,000.
Donald C. Shoup in 2005 argued in his The High Cost of Free Parking against the large consumption of land and other resources in urban and suburban areas for motor vehicle parking.
Parking Generation refers to a document produced by the Institute of Transportation Engineers (ITE) that assembles a vast array of parking demand observations predominately from the United States. It summarizes the amount of parking observed with various land uses at different times of the day/week/month/year including the peak parking demand. While it has been assailed by some planners for lack of data in urban settings, it stands as the single largest accumulation of actual parking demand data related to land use. Anyone can submit parking demand data for inclusion. The report is updated approximately every 5 to 10 years.