sentences:  The United States of America shares a unique and often complex relationship with the United Mexican States.With shared history stemming back to the Texas Revolution (1835–1836) and the Mexican–American War (1846–1848), several treaties have been concluded between the two nations, most notably the Gadsden Purchase, and multilaterally with Canada, the North American Free Trade Agreement (NAFTA).Mexico and the United States are members of various international organizations, such as the Organization of American States and the United Nations.