Especially in the last 50 years, innovations in air, rail, road, and sea transport technology, communications, and handling technology have caused cost/space (and time/space) to shrink, but differentially. These differential spatial effects largely stem from unequal investment in modal capacity, routes, and terminals at international, national, and local scales, and tend to enhance the importance of the largest demand centres in developed countries (Knowles (2006) J. Trans. Geog. 14, 6). See core–periphery.
Subjects: Earth Sciences and Geography.