House numbering

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House numbering is the system of giving a unique number to each building in a street or area, with the intention of making it easier to locate a particular building. The house number is often part of a postal address. The term describes the number of any building (residential or not) or vacant lot with a mailbox.

House numbering schemes vary by place, and in many cases even within cities. In some areas of the world, including many remote areas, houses are not numbered but named.

Early house numbering schemes were introduced in places, including the Pont Notre-Dame in Paris,^[1] as early as the fifteenth century. However, the purpose of the numbering was generally to determine the distribution of property ownership in the city, rather than for the purpose of organization.

It was in the eighteenth century that the first street numbering schemes were applied across Europe, to aid in administrative tasks and the provision of services such as the post. The New View of London reported in 1708, that " at Prescott Street, Goodman's Fields, instead of signs, the houses are distinguished by numbers".^[2] Parts of the Parisian suburbs were numbered in the 1720s; the houses in the Jewish quarter in the city of Prague in the Austrian Empire were numbered in the same decade to aid the authorities in the conscription of the Jews.

Street numbering took off in the mid-century, especially in Prussia, where authorities were ordered to "fix numbers on the houses...in little villages on the day before the troops march in". In the 1750s and 60s, street numbering on a large scale was applied in Madrid, London, Paris and Vienna, as well as many other cities across Europe.^[3]

In Australia and New Zealand, the current standard (Australia / New Zealand joint standard AS/NZS 4819:2003) for numbering newly created streets is to assign odd numbers to sites on the left and even numbers to the right when facing in the direction of increasing numbers (the European system). This standard came into force in 2003. Some exceptions exist where the road forms part of the boundary between different council areas or cities. For example, Underwood Road in Rochedale South has non-standard numbering, as it forms part of the boundary between Logan City and the city of Brisbane.

In New South Wales, the vast majority of streets were numbered before 2003 with odd numbers assigned to houses on the right of the street when facing in the direction of increasing numbers, and there is no plan to re-assign these numbers.

On some urban roads (e.g. Parramatta Road in Sydney) numbers will typically ascend until the road crosses a council or suburb boundary, then commence again at 1 or 2. Long roads can thus have several occurrences of each number. In semi-rural and rural areas, where houses and farms are widely spaced, a numbering system based on tens of metres or (less commonly) metres has been devised. Thus a farm 2300m from the start of the road, on the right-hand side would be numbered 230.^[4]

In Japan and South Korea, a city is divided into small numbered zones. The houses within each zone are then labelled in the order in which they were constructed, or clockwise around the block. This system is comparable to the system of sestieri (sixths) used in Venice.

In Hong Kong, a former British colony, the British and European norm to number houses on one side of the street with odd numbers, and the other side with even numbers, is generally followed. Some roads or streets along the coastline may however have numbering only on one side, even if the opposite side is later reclaimed. These roads or streets include Ferry Street, Connaught Road West and Gloucester Road.^[5]

In Europe the most common house numbering scheme is to number each plot on one side of the road with ascending odd numbers, from 1, and those on the other with ascending even numbers, from 2 or sometimes 0. The odd numbers are usually on the left side of the road, looking in the direction in which the numbers increase. Where additional buildings are inserted or subdivided, these are often suffixed a, b, etc. (in Spain and France, bis, ter, quater). Where buildings are later combined, they may use just one of the original numbers, combine them ("13/15"), or give their address as a range (e.g. "13–17"; not to be construed as including the even numbers 14 and 16). Where some plots are not built upon, there may be considerable gaps in the numbering scheme. If a lot of buildings are later built along a stretch of the street, either a range of unused numbers above the current highest house number may be used, introducing confusing discontinuities, or the remainder of the street must be renumbered.

In Haarlem, Netherlands, red numbers are used for upstairs apartments. In the Netherlands when more buildings are constructed than numbers were allotted when the street numbering was planned, discontinuity of numbering is avoided by giving multiple adjacent buildings the same number, with a letter suffix starting at "A".

In Venice, houses are numbered within districts known as sestieri, resulting in just six series for the entire city. In Genoa and in Florence houses are marked with black (sometimes also blue in Florence) numbers while businesses are usually (but not always) given red numbers, resulting in two distinct series for every street. The street numbers of businesses are denoted in writing (e.g., documents, online directories, etc.) by the addition of the letter "r" -- e.g., Via dei Servi 21r.

In Central and Eastern Europe, with the exceptions below, houses are typically numbered in the European style. Many streets, however, use the "boustrophedon" system described below.

In some Czech and Slovak cities and settlements, two numbering systems are used concurrently.

The basic house number is the "old" or "descriptive number" (Czech popisné číslo, Slovak súpisné číslo). The descriptive number is unique within the municipal part (a village, a quarter, mostly for one cadastral area) or within a whole small municipality.

For makeshift and recreational buildings in the Czech Republic, "registration number" (evidenční číslo) from a separate number series is used instead of the descriptive number. Somewhere, this number begins with zero or with the letter "E" or has different colour to distinction or contains words like "nouzová stavba" (= makeshift structure), "chata" (= ca. weekend house) etc.

In some of settlements where streets have their names (mostly in cities), there are used also the "new" or "orientation numbers" (Czech orientační číslo, Slovak orientačné číslo) concurrently. The orientation numbers are arranged sequentially within the street or square. If the building is on a corner or has two sides, it can have two or more orientation numbers, one for each of the adjacent streets or squares. Solitary houses distant from named streets often have no orientation number. In some places, the name of a small quarter is used as a street name. If there is a new building between two older numbered ones, the orientation number is distinguished with an additional lower case letter (the sequence could be 5, 7, 9, 9a, 9b, 9c, 11, 13). In the 1930s–1950s in Brno, lower case letters were used for separate entrances of modern block houses perpendicular to the street.

Either number may be used in addresses. Sometimes, businesses will use both numbers to avoid confusion, usually putting the descriptive (or registration) number first: "Hlavní 20/7." The two (or three) types of numbers are commonly distinguished by colour of the sign. Each municipality can have its own traditional or official rules and colours. In Prague and many other Bohemian cities, descriptive numbers are red, orientation numbers are blue and "evidential" numbers are green or yellow or red. In many Bohemian municipalities, descriptive numbers are blue, black or are not unified. In Brno and some Moravian and Slovak cities, descriptive numbers are white-black signs, orientation numbers are red-white signs. Many cities and municipalities have different rules.

Formerly, Roman numerals signifying the city district were added to the description number: e.g. "125/III" means descriptive number 125 in district number III (in Prague, this was Malá Strana). Roman numerals were used both in cities and in village municipalities with more settlements. Nowadays, the name of the settlement is preferred instead of Roman numerals.

The first descriptive numbering was ordered by Maria Theresa in 1770 and implemented in 1770–1771. The series was given successively as the soldiers went through the settlement describing houses with numbers. Thereafter, every new house was allocated the next number sequentially, irrespective of its location. Most villages still use their original number series from 1770–1771. In cities, houses have been renumbered once or more often in order to be sequential – the first wave of renumbering came in 1805–1815. In 1857, the Austrian Emperor allowed a new system of numbering by streets. This new system was introduced in the biggest cities (Prague, Brno) in the 1860s. In 1884, land registration books were introduced and they used the old (description) numbers as a permanent and stable identifier of buildings. The new (orientation) numbers continue to be used concurrently.

The double numbering also existed in some Austrian cities.

In Russia and many other former USSR countries, the European style is generally used, with numbers starting from the end of the street closest to the town center. Buildings or plots at street intersections may be assigned a composite number, which includes the number along the intersecting street separated by a slash (Russian: дробь), like in Нахимова, 14/41 (14 is the number along Nakhimova street and 41 is the number along intersecting street).

The odd numbers are usually on the left side of the road, looking in the direction in which the numbers increase; though in some cities (including Saint Petersburg) the odd numbers are on the right side.

In some cities, especially hosting large scientific or military research centers in Soviet time, the numbering might be different: houses may have numbers related to the block rather than the street, thus 12-й квартал, дом 3 (Block 12, House 3),^[6] similar to the Japanese and Korean systems (see below). Aktau is one example of this.

When a numbered plot contains multiple buildings, they are assigned an additional component of the street address, called корпус (building), which is usually a sequentially assigned number unique within the plot (but sometimes contains letters as in 15а, 15б, 15в and so on). So, a Russian street address may look like Московское шоссе, дом 23, корпус 2 (Moscow Street, plot 23, building 2), or Льва Толстого, дом 14б (Leo Tolstoy Street, plot 14, building b).

On very long roads in suburban areas kilometer numbering system also may be used (like Australian rural numbering system). For example, 9-й км Воткинского шоссе (9th kilometer of Votkinsk Highway), and Шабердинский тракт, 7-й км (7th kilometer of Shaberdy Road).

In many areas, particularly those in rural areas, many houses remain named but un-numbered. The odd numbers will typically, although not always, be on the left-hand side as seen from the centre of the town or village, with the lowest numbers at the end of the street closest to the town centre. Intermediate properties usually have a number suffixed A, B, C, etc., but there are several that have been given a half number, e.g. the old police station at 20½ Camberwell Church Street. At least one property (built next to no.2 after the street had been numbered) has been numbered zero.

Numbering all plots on one side of a street consecutively, continuing clockwise back down on the opposite side of the street – still exists, for example in Pall Mall, culs-de-sac, streets with buildings only on one side, some new towns, and in many villages in Wales. For instance, 10 Downing Street, the official home of the First Lord of the Treasury (usually the Prime Minister), is next door to 11 Downing Street, the home of the Second Lord of the Treasury (usually the Chancellor of the Exchequer). Houses which surround squares are usually numbered consecutively clockwise.

Before the early/mid nineteenth century, it was common in England for numbering to proceed sequentially along one side of the road and then back down the other (in a similar way to "boustrephedon" writing). Subsequent changes to local numbering can present pitfalls to researchers using historic street directories, for instance. If a street has no opposite houses, the convention is to number each plot with only odd numbers, starting at 1.

Some UK local authorities avoid the number 13 for house numbering, because that number is considered unlucky.^[7]

In the UK Fanlights were used in front doors, first introduced in the 1720s and these showed a unique representation of a house number to identify which house was which number.^[8] More recently, with the advent of contemporary architectural design and modern house building techniques, the house number has also evolved. House numbers today are frequently made from acrylic, aluminium and glass, along with more traditional materials such as ceramic, brass, slate and stone.

Some^[where?] countries in Latin America use systems similar to those in Europe. Houses are numbered in ascending order from downtown to the border of the city. In Mexico, the cities are usually divided in Colonias, which are small or medium areas. The colonia is commonly included in the address before the postal code. Sometimes when houses merge in a street or new constructions are built after the numbering was made, the address can become ambiguous. When a number is repeated a letter is added to the newest house. For example, if there are two 35's, one remains as 35 and the second one becomes 35A or 35Bis. In Venezuela houses, buildings, and streets have names instead of numbers.

It is sometimes common that in remote towns or non-planned areas inside the cities that the streets do not have any name and the houses do not have numbers. In these cases the address of the houses are usually the name of the person or family, the name of the area or town, and "Dirección Conocida" (Known Address), which means that the house of the family is known by almost all the community. This kind of addressing is only used in remote towns or small communities near highways. For people living near highways or roads the usual address is the kilometer of the road in which the house is established; if there's more than one, some references might be written or the "Dirección Conocida" may be added. In countries like Brazil and Argentina, but also in some villages in France, this scheme is used also for streets in cities, where the house number is the distance, measured in meters, from the house to the start of the street.

On most streets in the United States and Canada, odd numbers are on one side and even numbers on the other. Often, the number assigned is proportional to the distance from some baseline, so not all numbers are used. On very long roads, four- or five-digit addresses are common. In some places, such as Loudoun County, Virginia, almost all addresses contain five digits.

In cities with a grid plan of streets, addresses often increase by 100 for each cross street, though in some cities they are consecutive within each block, so that a block where one side is numbered 501, 503, 505, 507, 509, 511 is followed by a block beginning with 601. Generally, within a single city there is a single base point used for all addresses; numbering of all streets therefore reflects its distance from that base point, and directionals (north, south, east, west) are used to refer to buildings on streets which run in that direction and are in that direction from the base point. Most cities start their numbering from the base point in either single-digits or at 100. For example, if an address is located six blocks north of a city's base point, it would likely be numbered in either the 600 or 700 range and often the designator "north" added to the street name. This is often omitted if the street does not cross beyond the base point or changes names when doing so.

Addresses may also correlate with a street-numbering system. Thus, in Cleveland, Ohio, a building with the address 900 Euclid Avenue would be at the corner of Euclid Avenue and 9th Street.

Along the Overseas Highway in the Florida Keys, house numbers indicate their distance from Mile Marker 0 in Key West. The mileage is found by dividing the house number by 1000 (for example, 77220 Overseas Highway is 77.2 miles from Mile Marker 0).

Buildings in many rural areas in the United States used to lack these kind of addresses. Instead, an old rural address might have been simply "Rural Route 3, Box 15." However, the adoption of 9-1-1 emergency systems has required the adoption of street names and house numbers in rural areas, typically numbering 1000 for each mile from the nearest town center.

Carmel-by-the-Sea, California lacks any house numbering whatsoever. Houses are referred to, instead, as (for example) "Junipero 3 SW of 10th", meaning "The third house on the west side of Junipero, south of 10th."^[vague]

Block numbers are a system of assigning numbers based on distance rather than strictly sequentially. Typically, each block is assigned 100 numbers, such that the building numbers on that block vary only in the last two digits. For example, in Washington, D.C., the block of 7th Street, N.W., between D and E streets, N.W., is designated as the 400 block, meaning that building numbers on that block are in the range from 400 to 499 inclusive. It is common to indicate block numbers on street signs.

Often, when numbered streets are used, the address numbers on perpendicular streets will use the number of the lower-numbered cross street as the "hundreds" portion of the number for each block.

Some localities, such as the Borough of Queens in New York City, use a block numbering system in which a hyphen separates the hundreds digit from the tens digit. For example, a building number that might elsewhere be written 16709 is instead written 167-09. In most cases, the first number refers to the street, avenue, drive, etc. where the numbering begins. For example 99-40 63rd Road is numbered because the starting point was 99th Street. Likewise, an address on a perpendicular block would have its number starting with 63-XX. In Queens (unlike other areas, such as Los Angeles, where one may see numbers such as 16700 Sunset Blvd.) rarely is the 00 number used to refer to an address, but rather the numbering starts at -01 or -02 depending on the side of the block.