Connacht–Ulster was a constituency of the European Parliament in Ireland between 1979 and 2004. Throughout its history, it elected 3 Members of the European Parliament (MEPs) using the single transferable vote (STV) system. Although the constituency was abolished in 2004, Connacht-Ulster is still often used when analysing election results by region, as in this analysis of the results by region of the 2018 referendum to remove the constitutional prohibition of abortion.