The middle of the 20th century brought a rapid growth in the world population, later referred to as demographic explosion, the reasons for which are known. It led to accelerated urbanization, and thus an increase in urban population. It was the second stage of the rapid growth of cities, following one recorded two centuries earlier during the industrial revolution. Using this global processes as a background, this study presents the changes in population patterns of Polish cities – changes which were largely caused by factors different than those affecting the global situation. Currently, different urban development tendencies are observed all over the world. We are dealing with a slow-down resulting from ‘urban sprawl’, accompanied at the same time by practically uncontrollable growth of ‘megacities’. All these changes have been presented in this paper based on population statistics covering the last 50 years.

Keywords: city, agglomeration, metropolis, megacity.