n. — Politics
an organizational unit within a political party at the level of the electoral district.
Type: 5. Frequency — The term riding association had developed naturally from riding to describe a political party's base in a constituency. Since riding is primarily a Canadian term, it follows that riding association is also mainly found in Canada (see Chart 1).
See also COD-2, s.v. "riding association", which marks the term as "Cdn".
See also: riding (def. 2)
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Chart 1: Internet Domain Search, 5 Oct. 2012