Consequently, following the Anglo-Irish Treaty of 1921, these four counties – and two others in which they formed a sizeable minority near half the population – remained in the United Kingdom to form Northern Ireland.
Prema tome, uslijed Anglo-irskog sporazuma 1921. ove četiri županije – kao i druge dvije u kojima su tvorili značajnu manjinu blizu pola stanovništva – ostale su u Ujedinjenom Kraljevstvu u sastavu Sjeverne Irske.