The Trans-Mexican Volcanic Belt is an east-west, active continental volcanic arc which spans across central-southern Mexico from the Pacific Ocean for some 600 miles to the Gulf of Mexico between latitudes 18.5°N and 21.5°N. Furthermore, this 600 mile long passage of volcanic mountains spreads from 55 miles to 142 miles wide as it spans the region and encompassing an area of almost 62,000 square miles, (160,000 km2) or about 40 million acres. Too, this large volcanic belt rests upon the southernmost edge of the North American plate.

The Transcontinental Volcanic Mountain range, also known locally as the Sierra Nevada (Snow-covered Mountains) is a volcanic range which covers south central Mexico. As the name indicates, several of its highest peaks are covered with snow all year long. Furthermore, most of the people who live in south of Mexico can see these snow covered peaks, at least on clear days. This mountain range not only spans across Mexico from the Pacific Ocean to the Gulf of Mexico but also extends into the Pacific Ocean.

From the west, the Trans-Mexican Volcanic Belt traverses from off the Pacific coast, into Colima and Jalisco, then eastward through northern Michoacán, southern Guanajuanto, southern Querétaro, México State, southern Hidalgo, the Distrito Federal, northern Morelos, Puebla, Tlaxcala to central Veracruz.

To the north is the Mexican Plateau, which is bordered by the Sierra Madre Occidental in the west and Sierra Madre Oriental in the east. Then, to the south is the Basin of the Balsas River which lies between the Trans-Mexican Volcanic Belt and the Sierra Madre del Sur further to the south.

To the east, the Cofre de Perote volcano, (19.492, -97.15) fifteen miles west of Xalapa, Veracruz, is at the southernmost point of the Sierra Madre Oriental range at the point where the Sierra Madre Oriental joins the Trans-Mexican Volcanic Belt, and is just thirty-three miles north of the Pico de Orizaba volcano (19.03, -97.27) which is at the easternmost end of the Trans-Mexican Volcanic Belt, on the border between the states of Veracruz and Puebla and just 10 miles west of Cordoba, Veracruz.

When discussing plate tectonics, the Transcontinental Volcanic Mountains are as a whole referred to as the Trans-Mexican Volcanic Belt, which belt resides at the southern edge of the North American Plate. This belt, which is 622 mile long and 55-150 mile wide is an east–west, active, continental volcanic arc; encompassing an area of approximately 62,000 square miles. The primary tectonic plate which causes this belt of volcanoes to rise is the Cocos Plate.

The Cocos Plate is a young oceanic tectonic plate beneath the Pacific Ocean off the west coast of Central America, named for Cocos Island, which rides upon this plate. About 23 million years ago, the Farallon plate broke into two pieces forming the Cocos Plate in the north and the much larger Nazca Plate to the south. Then, about 10 or less million years ago, the Cocos Plate broke into two pieces creating the much smaller microplate to the northwest called the Rivera Plate and which lies under the Pacific ocean just south of the Baja Peninsula.

Both the Rivera Plate and the Cocos Plate are currently pushing under the North American plate, and the Cocos Plate from the Isthmus de Tehuantepec south to Costa Rica is pushing under the Caribbean Plate.

The subduction of these two Pacific plates beneath the North American Continent over the course of several million years has deepened the Middle American Trench and has formed this volcanic belt with many of the main stratovolcanoes positioned obliquely to the position of the subduction arc.