Included are data on the Portuguese urban centers with a resident population above 5000 inhabitants. The dataset can be used as a demographic criterium to analyse the Portuguese urban system, accepting the administrative boundaries that underlie the official statistics. A detailed check is made of small administrative units, called 'freguesias' for a considerably large number of communities. This is in order to stabilise their frontiers or to control their alterations throughout the period, according to meaningful criteria. This dataset is one of the results of the project EUROCIT which collects data on cities and urbanisation from several European countries.