Reinosa is a municipality located in the Cantabria region of northern Spain. As of 2009, the municipality had a population of 10,307 inhabitants. It is characterized by its small land area, ranking among the smallest municipalities in the region.
The town holds historical and geographical significance as one of the closest settlements to the headwaters of the Ebro River. It is geographically surrounded by the municipality of Campoo de Enmedio.
In 1927, King Alfonso XIII officially designated Reinosa as a city. This status makes it one of only three urban centers in Cantabria to hold the title, joining Santander and Torrelavega.