Republic of Ireland–United Kingdom border
Originally intended as an internal boundary within the United Kingdom of Great Britain and Ireland, the border was created in 1921 under the United Kingdom Parliament's Government of Ireland Act 1920. Prior to this, a separatist Irish parliament had been established in Dublin, which did not recognise the Government of Ireland Act, and was actively engaged in the Irish War of Independence. The Act was intended to deliver Home Rule in Ireland, with separate parliaments for Southern Ireland (which included three of the nine counties of Ulster) and Northern Ireland. Six of the thirty-two counties of Ireland were assigned to Northern Ireland, and the rest of Ireland comprising 26 counties to Southern Ireland.
Economic history of Ireland
After the War of Independence, most of Ireland gained independence from the United Kingdom. Twenty-six counties of Ireland became the Irish Free State, later described as the Republic of Ireland, while the other six remained in the Union as Northern Ireland. There had already been a significant economic divide between these two parts of Ireland, but following partition both regions further diverged, with Belfast, as the North's economic centre, and Dublin becoming the capital of the Free State. Partition had a devastating effect on what became Ireland's border area. County Donegal for example was economically separated from its natural regional economic centre of Derry. The rail network struggled to operate across two economic areas, finally closing across a vast swath of Ireland's border area (the only cross-border route left being that between Belfast and Dublin). The last remaining cross-border line (Belfast-Dublin) could not have operated after 1953 without government support.