Mexico is the most populous Spanish-speaking country in the world and the second most-populous country in Latin America after Portuguese-speaking Brazil. Highly developed cultures, including the Olmec, Maya, Toltec, and Aztec, existed long before Spain conquered Mexico in 1521. Mexico was a Spanish colony for 300 years until 1821 when it formally achieved independence. For 70 years, Mexico’s national government was dominated by the Institutional Revolutionary Party, or PRI, which won every presidential race until the July 2000 presidential election when Vicente Fox became the first president to come from the opposition. President Fox completed his term on Dec. 1, 2006, and he was succeeded by Felipe Calderon. Mexico is endowed with substantial natural resources, and is a major oil producer and exporter. The Mexican economy is highly dependent on exports to the United States, which account for about 90 percent of its total exports. Mexico has undergone a profound economic transformation since the mid-1990s as a result of economic liberalization and its joining the North American Free Trade Agreement (a free trade bloc with the U.S. and Canada also known as NAFTA). There has been rapid and impressive progress in building a modern, diversified economy, improving infrastructure, and tackling poverty. Today, the country enjoys a more open economic and political system and is more integrated with the world economy.