STOCKHOLM -- At the end of a long and intensely emotional campaign, Sweden has voted solidly in favor of abandoning its Arctic isolation and joining the European Union.


The vote Sunday -- billed as the most important decision this century for Sweden's 8.7 million citizens -- was 52.2 percent to 46.9 percent, with nearly 1 percent of the ballots left blank. The strong approval came as a surprise, with polls right up to voting day showing an even split and a fifth of voters undecided.


But the pro-EU campaign launched a strong last-minute push, with Social Democratic Prime Minister Ingvar Carlsson and his political rival, former Prime Minister Carl Bildt, arguing on the same side during a nationally televised debate.


Sweden's approval follows the passage of similar measures in Austria and Finland this year and is expected to give a boost to a referendum at the end of the month in neighboring Norway, where opposition has been strong.


The addition of all four countries would make the EU the world's largest and richest free-trade bloc, surpassing North America, and could help speed the integration of the eastern and central European countries hoping to join.


"This is a happy day," Carlsson said at a news conference following the vote. "We will be an active partner. This brings us new possibilities."


Sweden, a fiercely independent country connected to continental Europe primarily by ferries, was divided over whether joining forces with its neighbors would mean more or less employment, democracy and social welfare.


The issues of the campaign dug deep into the Swedish psyche. Fear ran high that entering the EU would compromise the country's commitment to political neutrality, human equality and environmental protection. For 150 years, Swedes have pursued a policy of neutrality that kept them out of two world wars and made them a buffer between the North Atlantic Treaty Organization and Soviet bloc nations.


But many Swedes have argued lately that neutrality is an outdated policy in the wake of the Cold War. And Sweden's economy is reeling from two decades of slow growth that has resulted in 14 percent unemployment and a budget deficit near 13 percent of the gross national product.


The pro-EU campaign, supported by most political leaders, big business and the country's largest national newspapers, clearly outspent opponents in pressing their case that this was the country's only chance to turn around the economy and prevent cuts in the country's generous social welfare system.


Carlsson also said that Sweden must have a voice in European economic and security policy decisions that inevitably affect the country. "I want us to be there when decisions are made, not just standing by hoping Finland and Denmark represent our interests," he said.


Support for the EU was greatest in the cities, among office workers and professionals. Opposition was strongest among environmentalists, farmers, workers and many women, all of whom feared economic intervention from Brussels, the seat of the EU, and a loss of sovereignty over political decisions.