In a much quoted study, BORNSTEIN & BORNSTEIN (1976) showed that the walking speed of pedestrians is positively correlated with the size of the city. They interpreted the higher walking speed of people in larger cities as a psychological response to stimulatory overload. We also found a positive correlation between walking speed and city size. In addition, we showed that - at least in our sample - larger cities had higher proportions of young males and lower proportions of people older than 60 years. Walking speed and momentary density did not correlate positively. Because walking speed is age- and sex-dependent (Fig. 2), differences in population structure are likely to cause differences in average walking speed. The average walking speed predicted for each city according to its age- and sex-composition correlated positively with city size. The regressions of observed walking speed on population size and of walking speed predicted from age structure on population size did no differ significantly in their slopes (p > 0.95). It therefore seems unnecessary to invoke other factors in addition to age composition to explain differences in average walking speeds of pedestrians.