The Trans-Mexican Volcanic Belt (Eje Volcánico Transversal) also known as the Transvolcanic Belt and locally as the Sierra Nevada (Snowy Mountain Range), is a volcanic belt that extends 900 km from west to east across central-southern Mexico. Several of its highest peaks have snow all year long, and during clear weather, they are visible to a large proportion of those who live on the many high plateaus from which these volcanoes rise.

From the west, it runs from Jalisco east through northern Michoacán, southern Guanajuato, southern Querétaro, México State, southern Hidalgo, the Distrito Federal, northern Morelos, Puebla and Tlaxcala, to central Veracruz. The Mexican Plateau lies to the north, bounded by the Sierra Madre Occidental to the west and Sierra Madre Oriental to the east. The Cofre de Perote and Pico de Orizaba volcanoes, in Puebla and Veracruz, mark the meeting of the Trans-Mexican Volcanic Belt with the Sierra Madre Oriental. To the south, the basin of the Balsas River lies between the Trans-Mexican Volcanic Belt and the Sierra Madre del Sur. This area is also a distinct physiographic province of the larger Sierra Madre System physiographic division.

A volcanic belt is a large volcanically active region. Other terms are used for smaller areas of activity, such as volcanic fields. Volcanic belts are found above zones of unusually high temperature (700-1400°C) where magma is created by partial melting of solid material in the Earth's crust and upper mantle. These areas usually form along tectonic plate boundaries at depths of 10-50 km. For example, volcanoes in Mexico and western North America are mostly in volcanic belts, such as the Trans-Mexican Volcanic Belt that extends 900 km from west to east across central-southern Mexico and the Northern Cordilleran Volcanic Province in western Canada.

The deeply deformed and eroded remnants of ancient volcanic belts are found in volcanically inactive regions such as the Canadian Shield. It contains over 150 volcanic belts (now deformed and eroded down to nearly flat plains) that range from 600 to 1200 million years old. These are zones of variably metamorphosed mafic to ultramafic volcanic sequences with associated sedimentary rocks that form what are known as greenstone belts. They are thought to have formed at ancient oceanic spreading centers and island arc terranes. The Abitibi greenstone belt in Ontario and Quebec, Canada is one of the world's largest greenstone belts.