It is often assumed that species generally reach their highest densities in the centre of their range and decline in abundance towards the range edges. A number of mechanisms have been proposed that could theoretically support this pattern, and several ecological theories have been developed based on the assumption that this pattern occurs in nature. However, few studies have quantified geographical patterns of species abundance throughout species ranges. This is largely because of the logistical challenges of sampling throughout the large spatial areas of most species ranges. We use intertidal invertebrates, which have relatively well defined linear ranges, to test the hypothesis that species are most abundant in the centres of their ranges.