In 1921 the Government of Ireland Act established two home rule parliaments in Ireland–the Parliament of Northern Ireland and the Parliament of Southern Ireland–and while STV was used for regular elections to these bodies, IRV was used for by-elections. This combination of IRV and STV has been used in what is now the Republic of Ireland ever since. The Northern Ireland Parliament continued to use the combination until the late 1920s when it switched to the 'first past the post' plurality system. However, STV for regular elections, and IRV for by-elections, has been reintroduced and used there to elect devolved assemblies since the 1970s.