While the winner of the longest federal campaign in recent Canadian history may not even be known by the time night turns to morning, trends in the hours leading up to the final call will provide some key insights into how things could shape up.
And there will be other developments, too, throughout the evening and even after all the results are in, that will be of interest.
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Here are seven things to look out for during election night:
As Atlantic Canada goes, so goes the election? Maybe not
With all the broadcast blackouts lifted, the first results will be trickling in from the East Coast, by about 7:30 p.m. ET. The Liberals are expected to nearly sweep Atlantic Canada, but their early success here is not necessarily indicative of how the rest of the evening will go.
"That doesn't necessarily presage anything," said Elly Alboim, associate professor in the school of journalism and communication at Carleton University. "Atlantic Canada has on several occasions bucked national trends and gone the other way."
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And if the Conservatives are able to hang on to a handful of seats, particularly in New Brunswick, it could be a sign that the night will not be as dour for the Conservatives as some have forecast. Of special interest will be Peter MacKay's former riding in Central Nova, Nova Scotia, and whether the Tories will be able to hang on to a riding that the former defence minister had held since 1997.
The battle for Quebec
It was the NDP's Orange Wave in Quebec that propelled Jack Layton and his party into the spot of official opposition. Their overwhelming dominance in the province, however, could be short-lived if the Liberals succeed in carving out a presence.
"If Quebec comes in hotter than 12 or 15 seats [for the Liberals], if it comes in with 30, then they may be heading into majority territory," Alboim said. "So watching the degree of breakthrough in Quebec may give you a hint about majority or minority."
Something else to watch for is whether the Conservatives will benefit from the niqab debate and see an expansion of their support beyond Quebec City and into the Eastern Townships. The Conservatives had been hoping to double their seat total to 10 from five.
For the NDP, Quebec is it, and if they can't hold the province, says Alboim, there's no reason to expect they can make big gains anywhere else.
"Quebec is their linchpin. You'll know their fate if they've hemorrhaged badly in Quebec."
Also, keep an eye on the Bloc, nearly decimated in the last election, to see whether their political fortunes will improve and if they can play any kind of spoiler role on the national stage.
Painting the GTA red over Tory blue
For the Tories, the story of the evening is all about counting losses. Ontario will be the first province where some of those losses are likely to stack up, most notably in the Greater Toronto Area. The Conservatives' great electoral success has been their significant breakthrough in the suburban areas around Toronto, where the Liberals lost all but one of their seats to the Conservatives in 2011.
Polls suggest the Liberals are poised to take most of those seats back, and how well they do here could be a sign of how things will shape up this evening.
"Virtually every seat is up for grabs, and the Liberals are currently favoured to prevail in the vast majority of them," wrote poll analyst Eric Grenier. "If they do, they will likely form the next government. But if the Conservatives can outperform expectations in just 10 seats, or even less, here, that could make the difference between a Liberal minority and a Conservative plurality."
Does it all come down to B.C?
It's become almost a Canadian election cliche, but with a three-way race in B.C., the winner could be decided in this province.
B.C. is usually a battle between the Conservatives and NDP, but one observer says the numbers are currently all over the map, with the Liberals competitive in a number of ridings.
"I think the odds are the election will be so close that B.C. will tell us if it's a minority and who the minority is for," said pollster Michael Marzolini. "Or, who gets the majority."
Get out the vote vs. the polls
The ability of the parties to get their supporters out come election day, the so-called ground war, could well be the deciding factor tonight. As Bill Tieleman, a communications consultant and former NDP strategist, recently told CBC News, a five per cent difference in polling means nothing on election day if a party can't get its vote out the door, or another party does it better.
This is an area where the Tories have traditionally had an advantage. Their voter base skews older and is much more likely to vote. As well, there may be a tendency for people to under-report their intention to vote Conservative, which may have an impact on polling.
Conservative strategist Jason Lietaer said the Tories usually receive a two to four per cent bump come election day.
The fate of cabinet
If much of Ontario falls to the Liberals, some of Conservative Leader Stephen Harper's most prominent cabinet ministers could fall with it. That would include Finance Minister Joe Oliver and Immigration Minister Chris Alexander in Ajax. Fisheries and Oceans Minister Gail Shea in P.E.I. is also in a tight race.
The fate of the leaders
It's possible that a straight loss could prompt Harper to resign this evening. Paul Martin stepped down on election night when he lost to the Conservatives in 2006. Even a minority win, with the party leaders vowing to topple his government, could have Harper contemplating his future.
NDP Leader Tom Mulcair has said he will not step down, but with polls suggesting a third-place finish, his position as party leader could be fragile.
The Greens and Bloc could be in line for new leadership if Elizabeth May is unable to expand her seat count and Gilles Duceppe's Bloc makes few gains or he fails to win his seat.
The only candidate whose future as party leader seems secure is Justin Trudeau. Even with a loss, the party is poised to, at the very least, triple its previous seat count, and could go much higher.
An earlier version of this story said Gail Shea is the minister of national revenue. She is in fact the minister of fisheries and oceans.Oct 19, 2015 8:13 AM ET