Isolationism not a solution - Mexican PM Enrique Pena Nieto.
Canada, the US and Mexico vowed to strengthen economic ties in the wake of the UK's decision to leave the EU and growing anti-globalisation sentiment.
"Isolationism cannot bring prosperity to a society," said Mexican President Enrique Pena Nieto.
Nieto's remarks came at the end of the Three Amigos Summit with US President Barack Obama and Canadian Prime Minister Justin Trudeau in Ottawa.
The three leaders reaffirmed their commitment to work together.
And they pledged to produce 50% of their countries' electricity from clean energy by 2025.
The show of unity comes at a time when questions are being asked of trade agreements.
British voters have opted to leave the European Union and US presidential candidate Donald Trump has vowed to renegotiate the North American Free Trade Agreement (Nafta).
Mr Obama said at the summit in Ottawa that he will keep working for a trans-Pacific trade deal.
That agreement is currently stuck in the US Congress and is opposed by both Republican Mr Trump and his Democratic rival, Hillary Clinton.
The US president said countries must not shut themselves off from the world and should instead strive towards an integrated economy and ways to raise standards for workers and the environment.
Mr Trudeau opened the conference by poking fun at President Barack Obama's impending retirement, to which Obama smiled and gave a thumbs up.
The three nations, which belong to the North American Free Trade Agreement (NAFTA), said a more integrated, united North America was vital to the both countries' and the global economies.
"We will build upon this strong trilateral economic relationship, and further facilitate trade among our three countries, and improve the networks that allow us to produce products and services together," the leaders said in a statement.
Analysis - Rajini Vaidyanathan, BBC News, Ottawa
As the rest of the world shrugs its shoulders at the unravelling of the EU-UK partnership, North American leaders are gathering to promote the strength of theirs. The summit is dubbed the "Three Amigos", but the friendship between the three hasn't always been as tight as that name suggests.
Canada's former Prime Minister Stephen Harper didn't see eye to eye with President Obama on a range of issues including climate change and the Keystone Pipeline, and both the US and Canada have had tensions with Mexico over immigration.
After a day of meetings with Mexico's President Enrique Pena Nieto on Tuesday, Justin Trudeau pledged to lift visa restrictions for Mexicans - in turn Mexico promised to lift a ban on beef exports - as a way to strength ties.
But as President Obama prepares to exit the White House, the balance of this trinity of leaders is sure to change, whether it's Donald Trump or Hillary Clinton in the White House.
"Better partnerships are a path to prosperity," Mr Trudeau said, ahead of the talks.
"And that's a compelling example that we want to showcase at a time where unfortunately people are prone to turning inwards, which will be at the cost of economic growth and their own success."
Tensions are mounting over the benefits of globalisation following the referendum in the UK, where many who voted to leave the EU expressed concern over border control and jobs.
US Republican presidential candidate Donald Trump has echoed similar sentiment, saying free trade has cost thousands of American jobs.
Mr Obama and Mr Trudeau are also expected to discuss international peacekeeping efforts in their bilateral talks behind closed doors, according to Canadian media.
Mr Obama will also address Parliament after the meeting.
It was announced this week that Mr Trudeau will appear as a cartoon character on the cover of an issue of Marvel in August.