Joseph Lawler writes for the Washington Examiner about key factors driving America’s housing crunch.

Decades of undersupply led to today’s housing crisis.

Several alternative competing explanations have been offered for why housing has become so unaffordable in recent months, including theories about demand-side factors, such as private equity firms and hedge funds buying up single-family homes or immigrants moving into neighborhoods.

But economists see years — decades, actually — of chronic undersupply as the underlying problem. Any other problems in the market are like speed bumps that cause a momentary slowdown, whereas the constraints on supply are more like an engaged parking brake that is making it harder for the car to get over each successive obstacle.

The problem came to a head this past year as mortgage rates soared even as housing prices have held near record levels or drifted even higher. The upshot has been that payments on newly purchased homes have soared, leading to a steep drop-off in home sales.

Homebuying, for now, has been pushed out of reach of many families.

Housing prices are now as high as they’ve ever been and well above the prices seen in the housing “bubble” years before the financial crisis in 2008.

The basic problem is a lack of supply.

“We have a crisis shortage of inventory of homes to buy,” said Mike Simonsen, president of the real estate analytics firm Altos Research. He noted that roughly 1.5 million new homes are needed yearly to replace old stock and keep up with population growth. Over the past decade, the country has built less than a million a year.

Rents, too, have risen faster than overall inflation for decades and have only accelerated in recent years. That suggests it’s not just speculation in real estate as an asset that has driven up prices but rather that the demand for shelter has been outstripping supply.