The land area including inland water and, in case of gminas located in the vicinity of internal sea waters - a part of such waters, lying within borders defined in the State Register of Borders and Area of Units of Administrative Division of Poland (in short - State register of borders).

The register held pursuant to the Geodetic and Cartographic Act dated 17 May 1989 (Journal of Laws of 2010 Nr 193 item 1287 with amendments). The area of the administrative unit is registered in the State register of borders, on the basis of which the administrative units and their area are defined as of 1 January of each year. Changes to the register are made pursuant to: - international agreements regarding the national border, - legal acts regarding the creation, merging, liquidation and division of national administrative units or changes of their borders, - legally binding administrative decisions as well as legally binding court rulings regarding property boundaries being at the same time borders of administrative units, - geodetic and cartographic reports accepted by the national geodetic and cartographic archives defining or defining in greater detail the location of border points.