Almost all of Mexico is on the North American Plate, with small parts of the Baja California Peninsula in the northwest on the Pacific and Cocos Plates. Some geographers include the portion east of the Isthmus of Tehuantepec including the Yucatán Peninsula within North America. This portion includes Campeche, Chiapas, Tabasco, Quintana Roo, and Yucatán, representing 12.1 percent of the country's total area. Alternatively, the Trans-Mexican Volcanic Belt may be said to delimit the region physiographically on the north. Geopolitically, Mexico is generally not considered part of Central America. Politically, Mexico is divided into thirty-one states and a federal district, which serves as the national capital.