The Oklahoma primary electoral system was a voting system used to elect one winner from a pool of candidates using preferential voting. Voters rank candidates in order of preference, and their votes are initially allocated to their first-choice candidate. If, after this initial count, no candidate has a majority of votes cast, a mathematical formula comes into play. The system was used for primary elections in Oklahoma when it was adopted in 1925 until it was ruled unconstitutional by the Supreme Court of Oklahoma in 1926.