What is the best way to describe the trade relationship between the united states and mexico?

"The U.S. is Mexico's biggest trading partner and Mexico is the U.S.'s third largest trading partners. In 2010, Mexico's exports totaled US$309.6 billion, and almost three-quarters of those purchases were made by the United States.

Several treaties have been concluded between the two nations bilaterally, such as the Gadsden Purchase, and multilaterally, such as the North American Free Trade Agreement. Both are members of various international organizations, including the Organization of American States and the United Nations."

wikipedia