There were, of course, small towns in Maine long before there were automobiles. But it’s worth pondering whether they will survive $4 or $5 gasoline.

Small towns sprung up where people earned their livelihoods – in Maine, that meant where there were farms, forests or fish. They were the thriving centers of social and business activity.

But, much has changed in the past 50 years. There are far fewer farms, and many of those still engaged in farming need to have at least one family member working off the farm.

Mechanization of the forest products industry has drastically reduced the number of human hands needed to turn a tree into a plank or a roll of paper. Meanwhile, fish stocks have declined and fishing methods have changed, resulting in far fewer jobs.

As a result, many of Maine’s small towns have lost population, particularly in northern counties without larger cities.

But, loyal residents have hung on, often by taking increasingly distant jobs in Maine’s service center communities.

Even those cities have commuter populations of their own. Far more Lewiston-Auburn residents commute to the Portland area than decades ago, while many in Portland and southern Maine travel to Boston or the towns in its suburban ring.

But the cost of oil may change everything.

Nationally, the exodus from small towns, according to Don Macke, head of the Center for Rural Entrepreneurship in Lincoln, Neb., will be far swifter than the gradual erosion that started with the end of World War II.

Americans have been moving toward cities and suburbs out of convenience; the next move, he says, will be out of necessity.

A 100-mile commute is expensive enough when gasoline is $2 per gallon, about $160 per month in a car getting 25 miles per gallon.

When the price of gas hits $5 per gallon, that same commute costs $400 per month. At that rate, a person earning $10 per hour is losing 25 percent of their before-tax earnings to gasoline. Add in car repairs and tolls, and a low-wage job may suddenly seem like a no-wage job.

Necessity is, of course, the mother of invention, and Americans are nothing if not inventive. More people will carpool, while computer technology may allow some rural residents to work from home. And who knows what the next round of technological innovation will bring, like a long-distance electric car.

But, for many rural residents, the crisis may arrive long before the solution, and they will be faced with a choice between moving closer to their jobs or maintaining their small-town way of life.

Most small towns will survive in some form in Maine and across the U.S. But will they have enough people to support schools, municipal governments and some level of commerce?

Unfortunately, only the world market for oil holds the answer.