Irish Protestants were mostly found in areas where British influence was strong. During the colonial era, the number of Protestants in the south was considerably high until Ireland was partitioned. The establishment of the Irish Free State and the end of the union between southern Ireland and Great Britain, who were the main protagonists in Protestantization of Ireland, is one of the main reasons protestant population declined significantly.
Though there are no exact figures, partitioning of Northern Ireland meant that protestant in the South hand to move to an environment that appeared to be more favorable to them. It is believed that close to 107, 000 Protestants moved to the north and the number of Protestants in the south dropped by 3% to reach 7%. This emigration brought with it some economic consequences, as Protestants formed the backbone of the economy at the time.
In recent years, there has been a significant increase in the number of Protestants in the Irish Republic. Notably, the primary beneficiaries of this increase are the major Protestant denominations Anglicans, Presbyterians, and Methodists. The reason for the growth in the south includes protestant immigration and the conversion of Catholics.