The leaders of the United States, Canada and Mexico begin a North American Leaders Summit in Mexico Sunday.

U.S. President Barack Obama, Canadian Prime Minister Stephen Harper, and Mexican President Felipe Calderon are holding a two-day meeting in Guadalajara. 

They are expected to talk about economic recovery and the increasing violence of Mexico's drug cartels. 

Canada is America's top trading partner.  Mexico is number three.

The two U.S. neighbors have criticized the "Buy American" clause in the $787 billion U.S. stimulus bill. The clause requires stimulus-backed public works projects to use U.S.-made materials, although Congress has made changes to the bill to include various exceptions.

Canada and Mexico say the requirement hurts businesses on their side of the border.

Mexico is also likely to seek a resolution of a trade dispute with the U.S. involving Mexican trucks.

The U.S. violated a NAFTA accord when it canceled a program allowing some Mexican trucks to operate in the U.S.  Mexico responded by imposing retaliatory tariffs of $2.4 billion on U.S. goods in March.

Other issues to be discussed at the summit include clean energy and the H1N1 swine flu which has spread through the U.S. and Mexico this year.

Some information for this report was provided by AFP and Reuters.