The United Mexican States, or commonly Mexico,is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the North Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of Mexico.The United Mexican States is a federation comprising thirty-one states and a federal district, the capital Mexico City, whose metropolitan area is one of the world's most populous.Covering almost 2 million square kilometers,Mexico is the fifth-largest country in the Americas by total area and the 14th largest in the world. With an estimated population of 109 million,it is the 11th most populous country and the most populous Spanish-speaking country in the world.As a regional power and the only Latin American member of the Organization for Economic Co-operation and Development since 1994, Mexico is firmly established as an upper middle-income country.Mexico is the 12th largest economy in the world by gross domestic product by purchasing power parity. The economy is strongly linked to those of its North American Free Trade Agreement partners. Elections held in July 2000 marked the first time that an opposition party won the presidency from the Institutional Revolutionary Party which had held it since 1929, culminating the political alternation at the federal level, which had begun at the local level during the 1980s.According to the World Tourism Organization, Mexico has one of the largest tourism industries in the world. In 2005 it was the seventh most popular tourist destination worldwide, receiving over 20 million tourists per year; it is the only country in Latin America to be within the top 25. Tourism is also the third largest sector in the country's industrial GDP.sThe most notable tourist draws are the ancient Meso-American ruins, and popular beach resorts. The coastal climate and unique culture – a fusion of European and Meso-American cultures; also make Mexico attractive. The peak tourist seasons in Mexico are during December and during July and August, with brief surges during the week before Easter and during spring break at many of the beach resort sites which are popular among vacationing college students from the United States.Mexico's middle/lower class typically take their vacations within Mexico, in contrast to the middle/higher class who travel worldwide, especially to Europe and the United States, and in lesser numbers to Asia and South America. Mexico is the twenty-third highest tourism spender in the world, and the highest in Latin America.