North America General info on House Numbers

In much of North America, buildings are not numbered according to a simple sequence but rather according to distance from a given baseline. As a result, four- and five-digit  numbers are common. Odd numbers are typically on one side of the street, evens on the other.

In cities with a grid pattern of streets, addresses often increase by 100 for each cross street. 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.

In San Francisco, parallel streets will sometimes be numbered in opposite directions. As an example, Broderick Street numbers ascend from south to north, while Masonic Avenue, just three blocks away, ascends from north to south.

Along the  in the Florida Keys, house numbers indicate their distance from Mile Marker 0 in Key West. The mileage is found by dropping the last three digits in the address (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.

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."

Block numbers

Block numbers are a system of assigning house 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 two least significant 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.

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.

Some localities in Utah and Wisconsin have a more elaborate system of block numbering. Such localities use compound block numbers to indicate the number of blocks from both the north-south and the east-west dividing lines. For example, an address in Utah might be of the form "226 N 3300 W" where other systems might use "226 33rd Ave NW". Another system, used in Wisconsin, might use "N112 W16709 Mequon Rd" rather than "16709 W. Mequon Rd". Such an address is in the northwest quadrant of the addressing system.