Source: UNCTAD.
The hierarchy of ports is often measured by the amount of traffic they respectively handle, with larger ports expected to rank higher, which is also referred to as a rank-size distribution. Still, the ordering of the ports also reveals another dimension of this hierarchy: the level of concentration. A hierarchy is usually not uniformly distributed; as ports grow more important, the benefits are commonly not linear. They accrue to a small number of ports that gain primacy since site, situation, and economic opportunities are not uniform. For instance, the top 10 container ports accounted for 32.8% of the global container throughput in 2023, underlining a high level of concentration. Together, the top 50 container ports account for 64.8% of global throughput.
A similar pattern applies to the liner shipping connectivity index (LSCI), but with a lower level of concentration. While the top 10 container ports account for close to one-third of the throughput, they account for less than 15% of the connectivity. This implies that connectivity has a non-linear relation with throughput, with increasing marginal benefits. Still, the top 50 ports account for 48.2% of the total connectivity.