Mariinsko-Posadsky District (; , SÃÂntÃÂrvÃÂrri rayonÃÂ) is an administrative and municipal district (raion), one of the twenty-one in the Chuvash Republic, Russia. It is located in the northeast of the republic. The area of the district is . Its administrative center is the town of Mariinsky Posad. Population: 26,959 (2002 Census); The population of Mariinsky Posad accounts for 38.0% of the district's total population.