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For other uses of this term, see city block (disambiguation).

Diagram of an example of a rectangular city block as seen from above, surrounded by streets. The block is divided into lots which were numbered by the developer as shown in red here and as shown in plats. The addresses on this example 800 block are shown in black and the adjacent blocks are the 700 and 900 blocks. An alley shown in light gray runs lengthwise down the middle of the block. Streets are shown in dark gray. Sidewalks are shown in light gray. Parkways are shown in green with walkways shown in light gray from every lot to the street.

A city block is a central element of urban planning and urban design. A city block is the smallest area that is surrounded by streets.

In most cities of the world that were planned, and did not develop and expand over a long period of time, streets are traditionally laid out on a grid plan, so that city blocks are square or rectangular. Using the perimeter block development principle, city blocks are developed so that buildings are located along the perimeter of the block, with entrances facing the street, and semi-private courtyards in the rear of the buildings.^[1] This setup is intended to provide good social interaction among people.^[1]

Since the spacing of streets in grid plans varies so widely among cities, or even within cities, it is impossible to generalize about the size of a city block. However, as reference points, the standard block in Manhattan is about 264 feet by 900 feet (about 80 meters by 271 meters), or slightly over five acres (two hectares); and in some U.S. cities standard blocks are as wide as 1/8 mile (660 feet or approximately 200 meters), or 10 acres (about 4 hectares) if square.

In most areas, cities have grown in a more amorphous manner rather than being planned from the outset. For this reason, an even pattern of square or rectangular city blocks is very uncommon in much of Europe. New York City adopted the Commissioners' Plan of 1811 creating an early example of the modern grid plan. In much of the United States and Canada, the addressing systems follow a block and lot number system, in which each block of a street is allotted 100 building numbers.

Superblocks were popular during the early and mid-20th century, arising from modernist ideas in architecture and urban planning. A superblock is much larger than a traditional city block, with greater setback for buildings, and is typically bounded by widely spaced, high-speed, arterial or circulating routes rather than by local streets. Superblocks are generally associated with suburbs, planned cities, and the urban renewal of the mid-20th century; that is, in areas in which a street hierarchy has replaced the traditional grid. In a residential area of a suburb, the interior of the superblock is typically served by cul-de-sac roads.

Urban planner Clarence Perry argued for use of superblocks and related ideas in his "neighborhood unit" plan, which aimed to organize space in a way that is more pedestrian-friendly and provided open plazas and other space for residents to socialize.^[2] In the 1930s, superblocks were often used in urban renewal public housing projects in American cities.^[3] In using superblocks, housing projects aimed to eliminate back alleys, which were often associated with slum conditions.^[3]

• Census block
• Minkowski space - One type of Minkowski space is sometimes known as "city-block space", with distance measured as Manhattan distance

1. ^ ^{a b} Frey, Hildebrand Frey (1999). Designing the City: Towards a More Sustainable Urban Form. E & FN Spon. 
2. ^ Keating, W. Dennis, Norman Krumholz (2000). "Neighborhood Planning". Journal of Planning Education and Research 20(1): p. 111-114. 
3. ^ ^{a b} Ben-Joseph, Eran, Terry S. Szold (2005). Regulating Place: Standards and the Shaping of Urban America. Routledge.