Shipping has been the key to prosperity and the very existence of many cities and nations since ancient times. It is difficult to think of any major metropolis that did not begin as a port. London originated as a Roman port, and ancient quays have been unearthed on the banks of the Thames River. From the Middle Ages to the Renaissance, Venice was one of the wealthiest cities and empires in the world because it controlled trade in the Adriatic Sea with, among other things, the thousands of ships its Arsenale churned out. Until the advent of railroads, it was usually cheaper to ship something 5,000 miles than transport it 50 miles overland.

The modern telecommunications revolution has only made this ancient form of transport more important. Factory managers in China and India communicate via computer with owners in Austin, Cupertino or São Paulo. They churn out iPhones, shirts and plastic toys, and put them into digitally labeled containers that go onto ships, where they are sent across oceans to be put on the beds of trucks or trains, and then transported to waiting warehouses or even directly into stores. There is always pressure to make things move faster with one less step.

Port cities have always scrambled to modernize, as well as to change through innovation. It’s generally agreed that New York City became the dominant North American city because New York state financed construction of the Erie Canal in 1817, which opened up the Midwest to international shippers via New York City.

A major event occurring now, scheduled for completion in 2014, is the expansion of the Panama Canal. The widening of this historic gateway between the Atlantic and Pacific oceans will allow enormous ships to leave places like Shanghai (now probably the world’s largest port), cross the Pacific Ocean, go through the Panama Canal and then sail on to Houston, New Orleans, Miami, Savannah, Charleston, Norfolk or New York City.

States and cities that support these sprawling port operations are scrambling to adapt, debating whether to spend the enormous sums of money necessary to deepen channels and expand facilities to handle these “post Panamax” and “new Panamax” ships. These ships are huge -- the largest are four football fields long, a football field and a half wide, and require a channel depth of 50 feet.

To handle these behemoths, the Port of New York and New Jersey, for example, must dredge its shipping channels to 50 feet from the present 40 feet. The “natural” depth of these channels is only 15 feet, so they must be dredged continually to maintain that depth. The New York/New Jersey port would also have to raise the Bayonne Bridge that connects Staten Island to New Jersey -- a billion dollar project -- to allow these super-sized ships to fit beneath it.

Meanwhile, the ports of Los Angeles and Long Beach, as well as the train and truck companies that interlink with it, are preparing for the day when ships have less of a reason to stop there.

Ports are funny things. They are essential to the prosperity of states and cities, but are largely invisible to residents. No longer do sweating gangs of stevedores unload sacks of coffee into downtown warehouses, as businessmen stop in their daily rounds to watch.

The 21st-century industrial term for moving stuff around is “logistics.” Like “infrastructure,” “logistics” is a modern, fancy word that replaces an older, simpler one: “shipping.” Our historic waterborne roots are evident in the fact that rail, road and air professionals call themselves “shippers,” and describe what they do as “shipping.” It’s even correct English to say, “the goods will be shipped by rail.”

The continual rise and importance of ports and the huge ships that service them have a number of implications, not all pleasant. The possibility of environmental and other sorts of “black swan” catastrophes is almost certainly made larger when so many eggs are put in one basket. But that’s a subject for another day. For now, give a nod to your port when you drive by. Your life is depending on it.