Transportation Cycle

Over time with the development of energy and infrastructure resources we have created larger and more powerful vehicles to move products from farm and factory to market. Recently in cities such as Portland and Amsterdam young progressives have been reverting to human power to move cargo. I see a possible trend here which you may find a bit circular. Recently, local bike stores have been offering an ever wider array of bicycles designed to carry cargo, as well as an assortment of bicycle trailers. Following is what I see as a natural sequence of development (or regression, depending on your point of view).

Obviously no captions required.