"Border area" was delimited on the basis of the definition included in the Regulation (EC) No 1931/2006 of the European Parliament and of the Council of 20 December 2006 on the assumption that gmina is the smallest administrative unit. An area of gminas reaching not further than 30 kilometers from the border has been assumed as a "border area". If a part of such a unit of administrative division is situated in a distance between 30 and 50 kilometers from the border line, it has been included in the border area.