"Hume was very much somebody who spoke about our common belonging to Europe as something that lifted us beyond the interior strifes and struggles that could happen between near neighbors. In other words, he was about bridges rather than borders," the archbishop said.
The border dates back to a partition agreement in 1921, leaving Northern Ireland predominantly with pro-union Protestants. The Republic of Ireland gained full independence in 1948. The following decades saw Irish Republican Army bombing campaigns along the border. This was followed by violence between republican and unionist paramilitaries within Northern Ireland itself, further complicated by British military intervention, from the late 1960s through the Good Friday Agreement signed in 1998.
The period of violence, collectively known as "the Troubles," killed 3,500 people, mostly non-combatants, Bloomberg News says.
The tensions, largely divided along Catholic-Protestant lines, resulted in many physical barriers. In the Northern Irish capital of Belfast, tall barricades still separate some Catholic and Protestant neighborhoods.
But following recent decades of stability, many young people have no memory of a physical border.
Some families have members on both sides of the border. Workers, businessmen, university students, shoppers and other visitors could face increased difficulties traveling to businesses or schools. Medical patients could be cut off from the closest hospitals.
Farmers and fishermen also face their own difficulties.
In the County Armagh border village of Jonesborough, one village church is in Northern Ireland, and its graveyard is in the Republic of Ireland.
Jonesborough area resident and farmer Damian McGenity told Public Radio International of his own fears.
"My wife works in the south, we get fuel and food in the south, I buy farm supplies in the south," he said. "Socially, if you go out to a restaurant, or see a football game, you would typically go to Dundalk in the south. All of that would be disrupted."
During the Troubles, the customs post at the nearby village Killeen was the site of many bombings and shootings.
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"Nobody wants to go back to any kind violence or trouble," McGenity said. "Absolutely not. But when you create the situation or the possibility of it, you take the lid off the Pandora's Box. It's madness, when there is complete peace here."
EU leaders have been negotiating in Salzburg and an EU leaders' summit is set for Brussels later this month. Oct. 17-18, Reuters reports. EU officials and diplomats hope for an agreement on a final withdrawal treaty offer, with further declarations on a future UK-EU trading relationship.
The situation is further complicated by the presence of the Democratic Unionist Party, the largest party in Northern Ireland, in the governing coalition of British Prime Minister Theresa May.
Mrs. May has agreed with Republic of Ireland leaders on the need for a "backstop" to ensure the border remains completely open to trade, people and services if no agreement is reached in time for formal UK withdrawal. At the same time, she has agreed to meet DUP concerns about maintaining its regulatory unity with the rest of the UK and preventing the creation of a border between Northern Ireland and the rest of the kingdom, which the DUP fears could further loosen political unity between the province and the rest of the country.
The EU is backing a "common regulatory area" between Ireland and the UK in Northern Ireland to protect its regulatory standards and its shared single-market between EU members. The UK Parliament remains divided between those seeking a "Brexit of least resistance" which would minimize economic and regulatory disruption, and those favoring a so-called "hard" or "clean" Brexit which, it is argued, could boost the UK's freedom to broker free-trade agreements with other countries.