accounted as about 1.2 million rather than the approximately 800,000 of the municipality, and Lund rather about 75,000 than about 110,000. Swedish definitions Terms used for statistical purposes () is the central concept used in statistics. The definition is agreed upon in the Nordic countries: An urban area is any village, town or city with a population of at least 200, for which the contiguous built-up area meet the criterion that houses are not more than 200 meters apart when discounting rivers, parks, roads, etc. – without regard to the ward, municipal or county boundaries. Delimitation of localities are made by Statistics Sweden every three years starting 2015 on a trial basis, previously they were made every five years. () is a rural locality with 50–199 inhabitants in a contiguous built-up area with no more than 150 meters between houses. The concept is rarely used outside the field of statistics, where it is used for settlements just below the limit defined for . Centralort () is mostly used in the meaning municipal seat or municipal center of service, commerce and administration for an area. Popular and traditional terms Storstad () is a term usually reserved for Sweden's three largest cities: Stockholm, Gothenburg and Malmö. Statistics Sweden uses the term metropolitan area () for these three cities and their immediate surroundings and municipalities. Stad () is the term avoided by Statistics Sweden, however, it roughly corresponds to urban areas with a population greater than 10,000. Judicially, the term stad has been obsolete since 1971, and is now mostly used describing localities which used to be chartered towns. The statistical category "large town" used by Statistics Sweden include municipalities with more than 90,000 inhabitants within a 30 km radius from the municipality centre. There is also a category medelstor stad "middle large town". Köping () was also abolished as an official term in 1971 in governmental and statistical contexts, and is only rarely kept in use by laymen, although it has survived as part of the names of several smaller towns. The meaning was a locality with an intermediary legal status below that of a town. Municipalsamhälle () was a term in use between 1875 and 1971, but it is no longer used outside of historical contexts. In 1863, Sweden was divided into 2,500 municipalities, whereof 89 were towns, 8 were market towns (köpingar) and the rest rural municipalities ("landskommuner"). A "municipalsamhälle"