President Bush has signed a pact with the leaders of neighbouring Mexico and Canada aimed at boosting security and economic ties.
Tensions between the three leaders are being kept out of the public eye
The security and prosperity partnership was launched at a summit with Mexican President Vicente Fox and Canadian Prime Minister Paul Martin in Texas.
But the BBC's James Coomarasamy in Washington says the three do not see eye-to-eye on every issue.
The summit agenda does not cover contentious areas in their relations.
Canada has decided no to enter the US missile defence programme, while Washington has accused Mexico of not doing enough to stem the flow of illegal immigrants across America's southern border.
The Mexicans, for their part, are concerned by the appearance of vigilante groups in states such as Arizona, ready to deal with new arrivals in their own way.
Mr Bush met Canadian Prime Minister Paul Martin and Mexican President Vicente Fox at Waco, after which they were due to fly by helicopter to his ranch at Crawford for lunch.
NORTH AMERICAN TENSIONS
Canada's refusal to sign up to missile defence
US restrictions on beef after mad cow cases
US punitive tariffs on lumber
Mexico high tax on soft drinks with corn syrup
US vigilante groups hunting illegals
US border walls
Alleged Mexican failure to stop al-Qaeda agents at border
"It is important for us to work together to make sure our countries are safe and secure," Mr Bush said at a joint news conference at Waco's Baylor University.
A joint statement by the three leaders mentioned collaboration in energy, transport, financial services and technology.
They also agreed to reduce costs of trade through "efficient movement of goods and people".
"In a rapidly changing world, we must develop new avenues of co-operation that will make our open societies safer and more secure, our businesses more competitive and our economies more resilient," the statement said.
Mexico said it would push for discussion of President Bush's stalled plan for a guest-workers' programme in the US where there are estimated to be nearly six-million undocumented Mexican workers.
Officials say Mr Fox and Mr Martin may have had an opportunity to raise difficult questions informally during the flight and over lunch.
However, meetings at President Bush's ranch in Crawford tend to be occasions for back-slapping, our correspondent says, so any tensions between the leaders are likely to be kept away from the public eye.