Aside from triggering turmoil in Europe, Brexit has exposed the fault lines dividing the U.K.’s four constituent pieces: Wales, Northern Ireland, Scotland and England. Add London to the mix, and Brexit makes clear that there’s nothing inevitable about a “United Kingdom” going forward. These five facts explain why.

1. Wales

In Wales, the ‘Leave’ side won with 52.5 percent of the vote. In the grand scheme of things, Wales poses nowhere near the threat that Scotland or North Ireland do to the U.K.—less than 5 percent of Welsh people want to declare independence from Great Britain. For comparison, 18 percent of Texans say they’d like to declare independence from the U.S. as recently as 2009.

Read More: Nicola Sturgeon Wants Scotland to Remain in the E.U.—But the E.U. Isn’t Sure

As for its attitudes toward the E.U., the irony is that Wales receives more payout from Brussels than it puts in—a net benefit estimated at $325 million per year. E.U. funding has created 36,970 new jobs for Welsh workers, and has helped more than 556,000 Welsh into work training. And the E.U.’s funding—$5.8 billion to the United Kingdom—sustain many projects and communities throughout the U.K. Whoever inherits the government will inherit a lot of communities with E.U.-sized expectations; it will be difficult to deliver on them all, especially with the recession that Brexit may well trigger.

(BBC (a), Financial Times, Huffington Post, ITV, BBC (b), The Guardian)

2. Northern Ireland

Like Wales, Northern Ireland depends on the E.U. for significant subsidies—nearly 90 percent of its farmers’ incomes come from E.U. coffers. Unlike Wales, North Ireland decided not to bite the hand that feeds, voting to Remain with 55.8 percent of the vote. But Northern Ireland has more at stake than financial concerns.

Read More: Why Brexit Means Scottish Independence Is Off The Table—For Now

A brief history: Predominantly-Catholic Ireland originally ‘exited’ the U.K. back in the 1920s, while predominantly Protestant Northern Ireland remained part of the U.K.. But Northern Ireland still has a sizeable Catholic community that continued to push hard for Irish reunification. After decades of violence, a peace was in place by the late 1990s. Crucially, because both the U.K. and Ireland were members of the E.U., there was no real need for borders between Ireland and Northern Ireland, once a flashpoint for violence. The Brexit vote has put that in jeopardy.

Sinn Fein, the pro-Irish reunification party, has already called for a referendum on reunification. Fortunately for the U.K., demographics are working against reunification at the moment, because polls suggest older voters are less supportive. But in another 10 or 15 years…

(Deutsche Welle, BBC, Al Jazeera)

Read More: The Brexit Vote Heralds a Return to the Grim 1930s for the Liberal World Order

3. Scotland

Scotland is a much more immediate flight risk. It not even two years since Scotland voted to ‘Remain’ part of the U.K. with a stronger-than-it-sounds 55 percent of the vote. It helped in 2014 that the Scots are staunchly pro-European—62 percent voted ‘Remain’ in the Brexit referendum—and voting to leave the U.K. would have meant leaving the E.U. The irony that the U.K. has now voted itself out—and the Scots along with them—has not been lost on Edinburgh (74 percent ‘Remain’). In a snap poll commissioned by The Sunday Times, 52 percent of Scots say they would vote to Leave the U.K. in a new referendum.

The number might be higher, but economic realities make another Scottish referendum unlikely at this point. An independent Scotland would rely heavily on oil sales to fund its economy, to the tune of nearly 20 percent. In June 2014, oil sold at $115 per barrel; today it sells at less than $50.

(BBC (a), BBC (b), Al Jazeera, The Sunday Times, The Telegraph, Bloomberg)

4. England

At the end of the day, the Brexit vote was decided in England, which makes up 84 percent of the U.K.’s overall population of 64.1 million (Northern Ireland = 2.9 percent; Scotland = 8.3 percent, Wales = 4.8 percent). Both migration and control of finances are legitimate concerns, and longstanding ones for the U.K.—outgoing PM David Cameron even renegotiated the U.K.’s membership in the E.U. a few months ago to better address them. It was not enough to placate the English, who voted to Leave at 53.4 percent.

But outside London, England has numerous communities that have been propped up by EU funding and subsidies. Cornwall is a county of 500,000 people that depends on $80 million a year from Brussels, but 56 percent of the county voted to Leave. Like Wales, it was only the day after the vote that the head of Cornwall’s Council scrambled to receive assurances—in writing this time—that Cornwall would continue to see this money. The U.K. could have survived Wales voting with its heart instead of its head; England in another matter.

(Office of National Statistics, BBC, The Washington Post)

5. London

Then there is London, an island of pro-European sentiment within an English sea of anti-E.U. anger. It’s no surprise that 60 percent of Londoners voted to Remain. London makes up just 12.5 percent of the U.K.’s overall population, but it’s responsible for 22 percent of the U.K.’s overall GDP thanks in no small part to its connections to the broader European economy. Also, London is home to 37 percent of those who live in the U.K. but were born abroad.

The real Brexit process, which will include negotiations with European leaders about the future U.K.-E.U. relationship, won’t begin until the fall. But it’s clear that Brexit has already given two constituencies with historical grievances more incentive to look beyond life in the U.K. Some decisions should be taken with the long game in mind. As we’ve just been reminded, that’s a perspective that voters don’t always bear in mind.

(BBC (a), BBC (b), House of Commons Library)

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