From Tamaulipas, the northeasternmost state in the Mexican Republic, 146 kinds of mammals, belonging to 72 genera, are here reported. Mammals that are strictly marine in habit are not included. The state is crossed in its middle by the Tropic of Cancer. Elevations vary from sea level on the Golfo de México to more than 2700 meters in the Sierra Madre Oriental; most of the state is below 300 meters in elevation. Its area is 79,602 square kilometers (30,732 square miles).

Tamaulipas, meaning “lugar en que hay montes altos” (place of high mountains), was explored in 1516 by the Spaniard Francisco Fernández de Córdoba, but it was not until the 18th century that José de Escandón established several villages in the new province of Nueva Santender from which, in the time of Iturbide’s Empire, Tamaulipas was separated as a distinct political entity, with about the same boundaries that it now has.