This article was originally published with the title “ Population Density and Social Pathology ” in Scientific American Magazine Vol. 206 No. 2 (February 1962), p. 139 doi:10.1038 ...

Because of this, exponential growth may apply to populations establishing new environments, during transient, favorable conditions, and by populations with low initial population density.

Population density (often abbreviated PD) is a compound measure that tells us roughly how many people live in an area of known size. It is commonly used to compare how 'built-up' two areas are.