The traditional counties of England are historic subdivisions of the
country into around 40 regions. They were used for administrative
purposes for hundreds of years, and over time became established as a
geographic reference frame. The usually-accepted set of counties was
established in the 12th century, although it did not become finalised
until the 16th century. After local government reform since the late
19th century, they are no longer in general use for geographic purposes
(in favour of ceremonial counties or administrative counties), but the
system in use is partially based on the traditional counties, and the
postal counties often still follow them.
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