San Mateo is one of the forty subbarrios of Santurce, San Juan, Puerto Rico. Demographics In 2000, San Mateo had a population of 1,989. In 2010, San Mateo had a population of 1,549 and a population density of 22,128.6 persons per square mile. Places The historic Church of San Mateo de Cangrejos of Santurce is in San Mateo, at Calle San Jorge and Calle San Mateo (one block from Avenida Juan Ponce de León). Gallery See also List of communities in Puerto Rico References Santurce, San Juan, Puerto Rico Municipality of San Juan