SummarySome remarks on the intensity of local telephone and postal traffic.In this paper a method is described to explain the trend of the intensity of the local telephone traffic in a certain area by means of the number of exchange lines, the telephone density (number of exchange lines per 1000 inhabitants), and the real national income per head of the population as explanatory variables. In connection with the intercorrelation between the number of exchange lines and the density, which would make the regression coefficients unreliable, the exponent of the number of exchange lines has been fixed by means of a cross section of telephone networks.The method was applied to the Amsterdam telephone network; it appeared that the development of the local telephone intensity over a long period could be explained satisfactorily. Further, extrapolation offers the possibility to estimate future investments.For the local postal traffic, too, it was examined whether the trend could be explained. It appeared, however, that it was not very well possible to do so because the basic data (which are nery difficult to collect in practice) were not sufficiently accurate. It was possible, however, to determine the relation, in a cross section, between the intensity of the local letter mail and the number of inhabitants per community.