riding wiki:
>This article is about the riding as a unit of local government and as an electoral district; for usage of the more common homonym, a form of the verb to ride, see horse and related articles such as riding animal. In the British Isles since Anglo-saxon times and in modern times in Canada, a riding is traditionally a sub-division (especially in three) of a county, in Australia analogous. The word is a corruption (known since 1295) of the Old Norse þriðing (thridhing or thrithing) meaning a third part (notably of a county). The term was also used in 19th century Canada to refer to sub-divisions of counties - today, the word riding is a semi-official term for an electoral district. A common misconception holds that the term arose from some association between the size of the district and the distance that can be covered on horseback in a certain amount time.
See more at Wikipedia.org...