Will tomorrow be Scotland's independence day?

Scotland holds a referendum tomorrow to decide whether to declare independence from the United Kingdom. This is no Putin-style hijacking of a disputed region, but the crescendo of a years-long, grassroots effort by the Scottish National Party to build a national identity and leverage it into independence. American media all but ignored the Scottish independence movement until the past month, when the real possibility of a divided United Kingdom hit home.

The latest polls show supporters of keeping the union with Britain have a razor-thin, four-point lead over those who favor independence. But the scales could tip in either side’s favor, depending on who turns out to vote.

With less than 24 hours until Scots go to the polls, here are some aspects of the issue to consider as the results come in:

This is a classic liberal vs. conservative drama. Scotland is a sparsely populated, predominantly middle-class country that took a huge economic hit from the decline of industry in the last century. “Between 1976 and 1987 the nation lost nearly a third of its manufacturing capacity,” historian Tom Devine wrote in London’s The Guardian. Many Scots blamed the Margaret Thatcher’s anti-union, pro-privatization reforms of the 1980s. In the last parliamentary election, which brought the conservative Tories back into power in the U.K., all but one of Scotland’s 59 seats in parliament went to the liberal Labour Party. Alex Salmond, claims Scots should have the power to find solutions to those problems on their own, free of British rule. His detractors accuse him of having unrealistic, sunny expectations for an independent Scotland, but they have struggled to come up with an alternative to present to his supporters, other than maintaining the status quo. Older Scots who oppose independence say the move brings too much economic and political uncertainty to the country’s future.

Scottish independence would come at a bad time for the United States. Britain and the United States have been co-leading the international response to two major crises: Russia’s incursion into Ukraine and the ISIS takeover of northern Iraq. U.S. President Barack Obama and U.K. Prime Minister David Cameron acted like bosom buddies at a NATO summit earlier this month, visiting a Welsh school together and publishing a joint editorial calling for an international coalition against ISIS. If Scotland gains independence, Cameron’s government could be mired down negotiating the 18-month transition. With no guarantees that an independent Scotland could join the European Union or NATO, would countries such as Russia try to snatch up Scotland as an ally before it established its place in the West? Probably not, but Scottish independence would undoubtedly bring a period of instability to Western Europe at a time when America needs it to be solid.

The Scots have a lot to lose, too. Scotland is known for its heavy government spending, and many pro-union supporters question whether it could support itself without help from the British government. Though the independence movement points to Scotland’s offshore oil as a source of revenue, that oil supply has dwindled in recent years, and Britain would have to agree to give up control over it. Scotland’s proportional share of Britain’s national debt would be astronomical for a fledgling country. Neither England nor the EU have promised to extend its currency to an independent Scotland. If Scotland has to create its own money, businesses could flee to avoid the cost of converting. As The Weir Group, a Scottish engineering firm, put it: “For businesses, the conclusions seem clear: The costs of independence are guaranteed but the benefits are uncertain.”

Don’t underestimate the power of Scottish nationalism. Even before William Wallace and Robert the Bruce became legends, the Scots managed to hold off the Romans, who built Hadrian’s Wall to defend southern Britain from northern “barbarians.” Scotland and England came under the same crown when a Scottish relative of Queen Elizabeth I succeeded her in 1603. But they maintained separate governments until 1707, when Scottish leaders turned to England for help repaying a massive debt it accrued in an attempt to colonize Panama. The unification was unpopular, and many Scots felt their leaders sold them out. In the last century, the class divide between England and Scotland has deepened. Scottish nationalists particularly despise Cameron, who attended elite private schools and has a reputation as a “Toff,” or dandy. Cameron has pleaded with the Scots not to judge all of Britain based on his background. “If you don’t like me, I won’t be here forever,” he said in a speech Monday.

After all, the British Empire isn’t what it used to be. When Scotland and England formed Great Britain in 1707, England was arguably the world’s strongest power. At the height of the British Empire in 1922, it ruled one-fifth of the world’s population. But since the end of World War II and the rise of the United States as a superpower, the U.K. has experienced what Winston Churchill tried to prevent: the liquidation of the British Empire. Though few predicted the decline would go this far, “the fact the referendum is being held at all,” Australian journalist Michael Sexton wrote, “underlines the decline of English culture and confidence across the past half century.”