Cheap housing, deep unease and intense resilience - all forces that are driving a clutch of Americans to swap city life for a fresh start off grid and far from civilisation.

Some are survivalists, among them high fliers who fear a looming, urban catastrophe and the mayhem that might follow.

Others want a greener, gentler life untainted by the malign forces of capitalism and uncertainty of mainstream politics.

Whichever camp, realtors say the new dropouts are not "crackpots" and often include affluent professionals whose run for the hills has boosted rural land values and started to change their property market.

"I've had hedge-fund managers and billionaires that have made purchases, and they all have concerns about the direction of the economy and social stability," said John E. Haynes, president of Retreat Realty in North Carolina.

"We're on that upward trend," he said. "Inventory of that land on the market is tighter."