"A NAFTA deal in principle will help ease investor anxiety, stabilize trade exposed sectors and reassure the world that North America remains committed to free trade", tweeted Rona Ambrose, who served until past year as interim Conservative leader before retiring from politics.
U.S. president Donald Trumps says the agreement was "truly historic".
"It'll probably or possibly be just USM".
Despite progress made to overhaul NAFTA, Trump still faces several other trade disputes around the world, not least with China, where the president has slapped a tariff on $200bn on Chinese imports.
Trump complained about the behavior of Canadian officials, and said he rejected a meeting with Prime Minister Justin Trudeau, although Trudeau's office said no meeting was planned. So the Americans got two things: "they've got access to the dairy market, the Canadian market, and they've also blocked us from their own market", he said.
The president has admitted there was "a lot of tension" but said it didn't affect negotiations.
Speaking at the White House, the President said the United States-Mexico-Canada Agreement (USMCA) vindicated his threats over tariffs.
Canada fought hard to retain Chapter 19, a holdover from NAFTA that US trade ambassador Robert Lighthizer worked tooth and nail to eliminate. Kushner played a similar role with Mexico - in that case, his close relationship was with Luis Videgeray, the Mexican foreign secretary, helped propel those talks to fruition.
Rather, the new agreement is being widely described as a "NAFTA-minus": a regime not as free as NAFTA had been, particularly in the automotive sector, but still very much in the interests of all three countries - and definitely better than no deal.
"We will continue to engage with USA and Canadian officials to seek a resolution of the tariffs on aluminum prior to final approval of the new agreement", Rio said in a statement.
The U.S. agreement with Ottawa will boost American access to Canada's dairy market - with some concessions on its heavily protected supply management system - while shielding the Canadians from possible U.S. auto tariffs.
The US and Mexico were pushing to get the new deal through their legislatures before Mexican President-elect Andres Manuel Lopez Obrador takes office on December 1.
The new agreement allows Canada to send 2.6 million passenger cars tariff-free to the United States in a year, well above the current level of 1.7 million. "Versus a very unpredictable and protectionist USA administration, I think Canada did as well as it could". He reiterated that the U.S.is now engaging in talks with the aim of preserving the current program and protecting industry needs.
A source told Reuters that Mr Trump had approved the deal.
It replaces the 24-year-old North American Free Trade Agreement, of NAFTA, which President Donald Trump had called a job-killing disaster.
NAFTA tore down most trade barriers between the United States, Canada and Mexico, leading to a surge in trade among them.
Trump has been pushing for a complete overhaul of the agreement which he says has been a "rip-off" for the United States.
Canada has offered access to its tightly controlled dairy market as part of other recent trade agreements.
US drug companies will also now be able to sell products in Canada for 10 years before facing competition from generics, up from eight years.
The lobby group says the measures will have "a dramatic impact not only for dairy farmers but for the whole sector", adding that it fails "to see how this deal can be good for the 220,000 Canadian families that depend on dairy for their livelihood".