Tamaulipas is a state in Northern Mexico.
Tamaulipas lies between Nuevo León and the Gulf of Mexico in the north of the country. It shares a border with the US state of Texas in the north and the states of San Luis Potosí and Veracruz to the south.
As of April 2011, Tamaulipas has become very unsafe even for Mexicans. The big problem now is the cartel wars (CDG, Z) that are terrifying all Tamaulipas. Traveling north to south has become very dangerous.
The San Fernando area (around 100 km from the north) is one dangerous spot these days. In this region was the discovery of an illegal graveyard where they found more than 100 bodies, some of them were slaughtered with cruelty by the Z cartel, so best not to visit Tamaulipas now. If you really have to, take some measures not to draw attention from drug cartels (no fancy clothes, not too much money, etc).