The area was inhabited by Indians on the banks of a narrow watercourse before the Spanish conquest. This watercourse was called Hum and now known as Black River.
In 1853, General Jose Gregorio Suárez founded there a town, on land donated himself and the area rancher Juan Cardozo. Gregory was called in honor of its founder, by referring to a Catholic saint according to the Spanish custom. He added, "Polanco" because the place was known before as "Paso de Polanco".
In 1945, the dam "Dr. Gabriel Terra "flooded low-lying areas nearby and changed the landscape of San Gregorio. Since then, the Hum indigenous widened, creating a lake of clear blue waters, which are reflected beautiful sunsets, and the spa was created.
That mirror of water, which has about 120 thousand hectares, with kilometers of white sand surrounding the peninsula, offers tourists and locals an ideal place to enjoy the sun and water during the summer stage, but also to admire the landscape any time of the year.
San Gregorio de Polanco was declared a town in 1963 and in 1995 city.