Central America is commonly said to include Guatemala, Belize, El Salvador, Honduras, Nicaragua, Costa Rica, and Panama. This definition matches modern political borders. Central America begins geographically in Mexico, at the Isthmus of Tehuantepec, Mexico's narrowest point, and the former country of Yucatán (1841–1848) was part of Central America. At the other end, before its independence in 1903 Panama was part of South America, as it was a Department of Colombia. At times Belize, a British colony until 1981, where English instead of Spanish is spoken, and where the population is primarily of African origin, has been considered not part of (Spanish-speaking) Central America.

From January 1822 to July 1823, the Captaincy General of Guatemala, a former Spanish colony, was controlled by the First Mexican Empire, and briefly, the Supreme Executive Power—the provisional government that succeeded Mexican imperial rule. The captaincy general consisted of the provinces of Chiapas, Costa Rica, El Salvador, Guatemala, Honduras, and Nicaragua—the six southernmost provinces of the Mexican Empire. The incorporation of Central America brought Mexico to the height of its territorial extent.