The North American urban grid systems (street naming and house numbering
systems) originated in several eastern cities platted in the late 18th
century, notably New York and Philadelphia. These systems were reportedly
inspired by ancient Roman grid systems as well as Cartesian coordinates. In
the Western states, the most highly standardized system is found in the many
cities and towns founded by the Mormon church.
In grid-street cities, street addresses (house numbers) are usually 100 per
standard block. When, as was often the case, streets were platted every
furlong (10 chains, or 8 streets per mile), a house number therefore
represents 0.1 chain or very close to 2 m. If house lots are a typical 1
chain wide, houses are thus numbered by tens (5200, 5210, 5220, or 5205,
5215, 5225, etc.), with even numbers on one side of the street and odd
numbers on the other, by convention. In large metropolitan areas laid out in
this system, one sometimes sees house numbers as high as 20000. In this
case, the house number tells you you're 2000 chains (or 2000 / 80 = 25
miles) from the "origin" of the city.
(Note: 1 Gunter's chain = 66 feet = 1/80 mile = 4 rods = 1/10 furlong = 20.1
m, so 0.1 ch = 6.6 ft = 2.01 m).
