Barack Obama, in his first foreign trip as US president, has pledged to work with Canada on energy, trade, economic recovery and Afghanistan.
In Canada's capital, Ottawa, he said global challenges, including security, required a global response.
He did not press PM Stephen Harper on the planned pull-out of Canadian troops from Afghanistan in 2011, he said.
Mr Obama also assured his country's biggest trade partner that he would not pursue protectionist policies.
"Now is a time where we have to be very careful about any signals of protectionism," Mr Obama told a joint news conference after talks with Mr Harper and senior members of his cabinet on the one-day visit.
As America's biggest trade partner, Canada is worried about the "Buy American" measures in Mr Obama's $787bn (£546bn) stimulus plan.
Under the provision, public works funded by the package should use only iron, steel and other goods made in the US, although the bill does state that international trade obligations will be respected.
One of the oddities of the Obama/Canada relationship is that he is so far to the left of Stephen Harper's conservative government
"If we pursue stimulus packages, the goal of which is only to benefit ourselves, or to benefit ourselves, worse, at the expense of others, we will deepen the world recession, not solve it," Mr Harper warned.
But Mr Obama stressed that the US would comply with its treaty obligations regarding international trade.
He said he wanted "to grow trade and not contract it".
The two countries are the world's largest trading partners, with about $1.5bn-worth of goods crossing the border each day.
Mr Obama announced a "clean energy dialogue" between the two countries to "advance carbon-reduction technologies" that will combat climate change.
The president received a warm welcome from the prime minister
It would also "support the development of an electric grid that can help deliver the clean and renewable energy of the future to homes and businesses" in both countries, the US president added.
Environmental activists have urged Mr Obama to get tough with Canada about its massive oil sands operation which produces a high amount of greenhouse gases blamed for climate change.
And on the war in Afghanistan, Mr Obama said he had not pressed Mr Harper on the Canadian decision to withdraw the bulk of its forces in 2011.
The US, concerned at the resurgent Taleban in Afghanistan, has said it will increase its forces in Afghanistan by 17,000, and expects allies to do more too.
"I certainly did not press the prime minister on any additional commitments beyond ones that have already been made."
Canada has about 2,800 troops in Afghanistan; 108 have been killed.
President Obama was greeted at Ottawa's airport by Canadian Governor General Michaelle Jean and an escort of Royal Canadian Mounted Police.
Ms Jean is a Haitian immigrant and Canada's first black governor general - the representative of Queen Elizabeth, Canada's titular head of state.
Busloads of Obama supporters went to Ottawa, hoping for a glimpse of the president, in contrast to the thousands of protesters who descended on the capital for President George W Bush's visit in 2004.
Mr Obama is very popular in Canada: 66% of Canadians wanted him to be president, according to a Gallup opinion poll.
About 2,000 people braved the cold, snowy weather to get a glimpse of the president as he met Mr Harper at the parliament building and turned to give the crowd a wave.
Mr Obama also met opposition Liberal Party leader Michael Ignatieff before he returned to Washington.
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