sentences:  The Gostynia river, a tributary of the Vistula, flows through Tychy.Since 1999 Tychy has been located within the Silesian Voivodeship, a province consisting of 71 regional towns and cities.Tychy is also one of the founding cities of the Metropolitan Association of Upper Silesia, a pan-Silesian economic and political union formed with the eventual aim of bringing the most populous Silesian areas under a single administrative body.