US unions have condemned the pact, saying it has contributed to rising unemployment in the US by encouraging employers to use cheaper labour elsewhere.
 
With a combined gross domestic product of $15 trillion, the three countries are each other's top trading partners, exchanging goods and services worth nearly $900bn in 2007 - about $2.4bn a day.
 
Hurricane damage
 
The annual summit is officially billed as the Security and Prosperity Partnership of North America, a dialogue begun in 2005 to discuss security and economic issues.
 
Opening the summit, Bush said he chose New Orleans as the host city to show that it was recovering from the devastation wrought by Hurricane Katrina in 2005.
 

"I wanted to send a clear signal to the people of my country that New Orleans is open for business," Bush said.

 

Immigrants from Mexico and across Latin America have worked to rebuild the city, and tens of thousands now live in the New Orleans area.

 

Calderon is expected to push the US to pass immigration reform at the summit.

 

"I know that thousands of Mexicans have participated in the reconstruction of New Orleans," Calderon said.

 
"I'm very happy today to see New Orleans standing and working."
 
However, large parts of New Orleans and the Gulf of Mexico coast remain damaged while local governments struggle to rebuild.
 
Rent has increased by more than 40 per cent since the disaster and homelessness has doubled, according to reports.