Mexico, officially the United Mexican States, is a country in the southern portion of North America. Covering 1,972,550 km2, it is the world's 13th largest country by area; with a population of almost 130 million, it is the 10th most populous country and has the most Spanish speakers in the world. Mexico is organized as a federal constitutional republic comprising 31 states and Mexico City, its capital and largest city, which is among the world's most populous metropolitan areas. The country shares land borders with the United States to the north, with Guatemala and Belize to the southeast; as well as maritime borders with the Pacific Ocean to the west, the Caribbean Sea to the southeast, and the Gulf of Mexico to the east.