LONDON — The United Kingdom voted to end 43 years of European Union membership after a divisive referendum campaign that prompted Prime Minister David Cameron to announce he would resign. The vote sent global markets crashing over the potential dismantling of a union designed to ensure peace and security for a continent ravaged by two world wars.
The margin of victory was 52% to 48%. Cameron, who had campaigned to remain in the 28-member EU resigned shortly after the final result from Thursday's vote was announced.
The outcome means that the U.K. will now spend up to two years launching a process to renegotiate its trade, business and political links with a bloc that will have 27 members. It is an unprecedented separation that could take far longer to complete.
“The dawn is breaking on an independent United Kingdom,” said Nigel Farage, leader of the U.K. Independence Party. “Let June 23 go down in our history as our independence day.”
Farage's party opposes the wave of migrants pouring into Europe from the Middle East and North Africa, a crisis that became a major reason cited by those favoring an exit from the EU, which sets immigration policy for member nations.
Cameron, leader of the ruling Conservative Party, said he will go by October after a period of transition to calm anxieties.
“I will do everything I can as prime minister to steady the ship over the coming weeks and months,” he said, “but I do not think it would be right for me to try to be the captain that steers the country to its next destination.”
The British pound fell 11% to a 31-year low on the result, and Dow futures plummeted more than 600 points. Britain's main stock index, the FTSE 100, nosedived 8.7% to 5,790.
Markets were also volatile in Asia. Japan's Nikkei 225 average dropped more than 1,200 points, or 8%.
The Bank of England — the U.K.'s central bank — said it was monitoring developments closely and "has undertaken extensive contingency planning."
"I want to reassure everyone that we are prepared also for this negative scenario," said Donald Tusk, president of the European Council, which is made up of leaders of EU member nations.
"There's no hiding the fact that we wanted a different outcome of yesterday's referendum. I am fully aware of how serious, or even dramatic, this moment is politically," he said in a statement.
Tusk said the remaining leaders "are determined to keep our unity as twenty seven."
James Sloam, the co-director of the Center for European Politics at Royal Holloway, University of London, said the U.K. would be "in limbo" until a new leader is chosen.
Boris Johnson, the former mayor of London, is seen as a possible successor to Cameron.
Johnson and Justice Secretary Michael Gove, Conservative Party leaders of the official “leave” campaign, paid tribute to Cameron after his resignation. Johnson made no mention of the possibility of replacing Cameron as prime minister or leader of the Conservative Party.
Johnson said it was Cameron's "bravery" that enabled the referendum, adding that the opposite of isolationism was true.
“This does not mean the United Kingdom will be any way less united (or) any less European,” he added. “We cannot turn our backs on Europe, we are part of Europe.”
The White House said Friday, "We expect the president will have an opportunity to speak to Prime Minister Cameron over the course of the next day, and we will release further comment as soon as appropriate."
Iain Murray, vice president for strategy at the Competitive Enterprise Institute, a Washington public policy organization, said Britain’s "surprising vote" to leave the EU is "only the start of uncertainty and opportunity."
"Negotiations over the terms of exit will take at least two years, and no one knows what form they will take or what deal can be struck,” he said.
The four-month campaign was acrimonious. Exit backers argued that severing ties with the EU is the only way to reduce a flood of migrants and protect the U.K.'s independence from burdensome economic and social regulation. The "remain" camp said leaving the EU would hurt the United Kingdom's economy and weaken its national security.
The impact on the EU is unclear but it could trigger moves by other Euro-skeptic members such as the Netherlands to try to hold similar referendums. The EU's single market of 500 million people is the world’s largest economy. There also could be a renewed attempt by Scotland to launch a second independence bid.
Scottish First Minister Nicola Sturgeon, the leader of the Scottish National Party, said she will push for a referendum to decide whether her country should remain part of the U.K. Scots voted overwhelmingly to stay in the EU in Thursday's polls. Scotland failed to win independence in a 2014 vote among Scots.
Author J.K. Rowling tweeted early Friday: "Scotland will seek independence now. Cameron's legacy will be breaking up two unions. Neither needed to happen."
The Electoral Commission said a record 46.5 million people registered to vote. The question on the ballot paper was: "Should the United Kingdom remain a member of the European Union or leave the European Union?"
It was the U.K.'s third nationwide referendum, and its second on EU membership. U.K. voters backed staying in the EU in 1975.
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