New York City (officially The City of New York) is the largest city in the United States, with the New York metropolitan area ranking among the largest urban areas in the world. For more than a century, it has been one of the world's major centers of commerce and finance. New York City is rated as an alpha world city for its global influences in media, politics, education, entertainment and fashion. The city's cultural centers for arts are among the nation's most influential. The city is a major center for foreign affairs, hosting the headquarters of the United Nations. Residents of the city are known as New Yorkers. The current mayor of New York City is Michael Bloomberg.