It originates on the Mexican Plateau in the states of San Luis Potosí and Guanajuato, and flows westwards.

For much of its length, it forms the border between San Luis Potosí and Guanajuato.

It carves a canyon through the Sierra Madre Oriental, where it is joined by the Rio Verde.

The Tampaón continues westwards to join the Moctezuma River and form the Pánuco River, which empties into the Gulf of Mexico at Ciudad Madero.

This article related to a river in Mexico is a stub.