Millions of Americans are heading to the polls Tuesday as a chaotic presidential campaign reaches its peak in a deeply divided United States, where voters in only a handful of battleground states will choose the country鈥檚 path forward.

Vice-President Kamala Harris and former president Donald Trump have presented starkly different visions for America鈥檚 future, but polling shows the two remain in a dead heat.

鈥淎ny election in the U.S. is important and impactful for us,鈥� said Kirsten Hillman, Canada鈥檚 ambassador to the United States. 鈥淭hey are central to our economic prosperity. They are a vital security partner.鈥�

Hillman has been travelling across America meeting with key members of the Republican and Democrat teams to prepare for any outcome. On election night, after her embassy duties are finished, she鈥檒l be watching the results with her husband and friends 鈥� and said she鈥檚 leaning toward ordering pizza.

While the gathering with loved ones may bring solace amid the anxious anticipation, Hillman knows more than anyone the immense stakes at play for Canada.

鈥淲hoever is sitting in the Oval Office and populating Congress is making decisions that may affect Canada, either decisions that provide us with opportunities or decisions that pose challenges for us,鈥� Hillman said. 鈥淭he job is to be ready for both.鈥�

A shared history and 8,891-kilometre border will not shield Canada from the election鈥檚 outcome. Both candidates have proposed protectionist policies, but experts warn if the Republican leader prevails the relationship between the neighbours could be much more difficult.

鈥淭rump and some of the key people around him, including (former trade representative) Robert Lighthizer, really want to stick it to Canada,鈥� said Fen Hampson, a professor of international affairs at Carleton University in Ottawa.

Trump鈥檚 first administration demonstrated how vulnerable Canada is to America鈥檚 whims when the former president scrapped the North American Free Trade Agreement.

Negotiating its successor, the Canada-U.S.-Mexico Agreement, was a key test for Ottawa after Trump鈥檚 victory. Whoever takes over the White House this time will be in charge during the agreement鈥檚 review in 2026.

A cause for concern in Canada and around the world is Trump鈥檚 proposed 10 per cent across-the-board tariff. A Canadian Chamber of Commerce report suggests those tariffs would shrink the Canadian economy, resulting in around $30 billion per year in economic costs.

American economists warned Trump鈥檚 plan could cause inflation, and possibly a recession, which would almost certainly have ripple effects in Canada. More than 77 per cent of Canadian exports go to the U.S and trade comprises 60 per cent of Canada鈥檚 gross domestic product.

鈥淲hen the American economy is growing, it鈥檚 generally good for us,鈥� Hampson said. 鈥淚f they take a deep dive under Trump 鈥� that will have a knock-on effect on us, on top of tariffs.鈥�

The election outcome could also redefine America鈥檚 role in the world. Trump is critical of giving aid to Ukraine in its war against Russia, has attacked the United Nations and repeatedly claimed he would not defend NATO members that don鈥檛 meet defence spending targets 鈥� something Canada is not doing, and won鈥檛 for years.

Prime Minister Justin Trudeau promised to meet the target of spending the equivalent of two per cent of GDP on defence by 2032.

Trump鈥檚 first tenure also saw the Republican leader withdraw from the Paris Agreement, an international treaty to cut greenhouse gases.

Hampson said the Republicans鈥� push against international institutions and treaties will have 鈥渁 profound impact鈥� on Canada, but also key allies and the world order itself.

If Harris wins, it鈥檚 widely expected that there will be more normal relations based on established patterns and rules, but it does not necessarily mean smooth sailing for Canada.

It鈥檚 expected the vice-president would follow the path laid by President Joe Biden on foreign policy and trade with Canada.

Biden signed an executive order to revoke the permit for the Keystone XL pipeline, which would have transferred oil from Alberta to Nebraska. The administration鈥檚 Buy America procurement rules also caused concern in Canada.

Laura Dawson, an expert on Canada-U.S. relations and the executive director of the Future Borders Coalition, said she expects a Harris administration would continue nationalist and protectionist policies.

Harris has spoken on the campaign trail about the fact that she voted against the trilateral trade agreement and said she will return manufacturing jobs to the U.S.

It鈥檚 a great slogan and bumper sticker, Dawson said, 鈥渂ut it鈥檚 terrible if you are Canada.鈥�

Dawson warned Trudeau鈥檚 team during a cabinet retreat in August that no matter who is the next president, Canada will have to work harder to maintain existing benefits of integrated trade and travel.

Meanwhile, many Americans are caught between anxiety and excitement. Sixteen-year-old Gavin Kupcho attended his first Trump rally in Wisconsin last week.

鈥淚鈥檝e never felt more enthused in my life,鈥� he said. 鈥淚 need lower gas prices since I just got my licence.鈥�

The situation feels more dire for Antonio White, who travelled from Miami to Milwaukee to knock on doors for Harris in the crucial battleground state. The 63-year-old said America is at a critical point 鈥渨here people are no longer recognizing fascism when they see it.鈥�

鈥淭his is an election we must win for the sanctity of everybody, for the country itself,鈥� he said.

鈥淒emocracy is on the ballot this time.鈥�