Co-operation and Development OECD (since 1994), and considered an upper-middle income country by the World Bank. Mexico is considered a newly industrialized country and an emerging power. It has the thirteenth largest nominal GDP and the eleventh largest by purchasing power parity. The economy is strongly linked to those of its North American Free Trade Agreement (NAFTA) partners, especially the United States. Mexico ranks sixth in the world and first in the Americas by number of UNESCO World Heritage Sites with 31, and in 2007 was the tenth most visited country in the world with 21.4 million international arrivals per year.