Research on the evolution process of U.S. container port system

以美国集装箱港口体系的相对集中度为标准,通过计算1970—2009年的赫芬达尔—赫希曼指数,在参考1970—2009年美国集装箱港口数量、集装箱吞吐量以及港口的空间变化基础上,将美国集装箱港口体系演进过程划分为四个阶段,即1970—1981年的快速分散阶段、1981—1995年的缓慢分散阶段、1995—2006年的缓慢集中阶段以及2006—2009年的再次分散阶段。从美国集装箱港口体系的演进过程中可以发现,美国集装箱港口体系发展存在周期性;并在1995年之后形成了较为稳定的多中心的集装箱港口网络,且某一区域的货运中心并非都是一港独大的。||The U.S. container port system evolution process from 1970 to 2009 can be divided into four phases by its concentration degree,which is presented by Hirshmann-Herfindahl Index(HHI).Annual number,throughput and spatial change of U.S.container ports are also considered in the research.The four stages are:quick deconcentration phase(1970-1981),mild deconcentrating phase(1981-1995),regularly concentrating phases(1995-2006) and the second deconcentration phase(2006-2009).The evolution of U.S.container port system has shown periodicity during 1970-2009 and a container port network with multiplied load centers has formed along the American coastline since 1995.This analysis also proves that there are more than one load centers in certain regions of the port network.