Arpent

An arpent is the name given to a unit of length and to a unit of area. It is not an SI unit. It is used in Quebec as well as in some areas of the United States that were part of French Louisiana.

Unit of length
There were various standard arpents. The most common ones were of 180 french feet, used in French North America, and 220 French feet, used in Paris.

1 arpent = 180 French feet (of approximately 32 centimetres) = about 192 English feet = about 58.47 metres

Unit of area

 * Historically, in North America, 1 (square) arpent = 32,400 French square feet = about 3419 square metres
 * In Louisiana, Mississippi, Alabama, and Florida, the official conversion is 1 arpent = 0.84628 acre = 3424.77365 square meters
 * In Arkansas and Missouri, the official conversion is 1 arpent = 0.8507 acre = 3442.66076 square meters

Origin
The arpent was a pre-metric French unit. Its is based on the actus, one of the Ancient Roman units of measurement.

Arpents in U.S. land descriptions (Louisiana)
In Louisiana, parcels of land known as arpent sections or French arpent land grants also pre-date the Public Land Survey System (PLSS), but are treated as PLSS sections. An arpent is a French measurement of approximately 192 feet (59 m), and a square arpent (also referred to as an arpent) is about 0.84 acre.

French arpent land divisions are long narrow parcels of land usually found along the navigable streams of southern Louisiana, and also found along major waterways in other areas. This system of land subdivision was begun by French settlers in the 1700s, according to typical French practice at the time and was continued by both the Spanish and by the American government after the acquisition of the Louisiana Purchase. A typical French arpent land division is 2 to 4 arpents wide along the river by 40 to 60 arpents deep, while the Spanish arpent land divisions tend to be 6 to 8 arpents wide by 40 arpents deep.

This method of land division provided each land-owner with river frontage as well as land suitable for cultivation and habitation. These areas are given numbers just like standard sections, although the section numbers frequently exceed the normal upper limit of 36.