Population density zones
The map is constructed by moving a circle with a radius of 30 km step by step over the whole country. At each step the number of inhabitants within the circle is worked out from the coordinate-designated real estates and the population register and referred to the central point of the circle. The values were grouped in classes and the map generalized by isarithms, lines joining points of equal value. A circle with a 30 km radius corresponds approximately to the commuter area. A clear map of population density zones emerges, showing not the least the vast areas of extremely sparse population and the three main urban centres, Stockholm, Göteborg and Malmö.