Americans are stuck. Locked into our jobs, rooted where we live, frozen at our income levels. More than at any previous point in our history, we’ve stopped moving — whether moving up the income ladder or packing up a truck and finding another home. We’ve grown ossified, rigid.

The flip side is that we’re stable. If we weren’t so content, we’d be more willing to gamble, to shake things up, to start a new firm or join one. Maybe we’re fine where we are. But maybe this period of stasis cannot last. Maybe it even portends a period of massive disruption.

In “The Complacent Class: The Self-Defeating Quest for the American Dream,” economist Tyler Cowen presents an X-ray of societal sclerosis. This isn’t merely another exercise in nostalgia, a sentimental yearning for a bygone era (when, for instance, crime and pollution were higher, people were highly likely to marry someone who lived within five blocks and you would buy an album containing 10 lousy songs because you liked one track). Something has changed in the American character and in the American economy, and the two seem to be reinforcing each other.

For instance, parts of the country (New York City, Silicon Valley, Texas) are doing extremely well, yet able-bodied adults sit idle in other areas. Why don’t the unemployed, and the large numbers who have dropped out of the labor force, move to the boom towns? Wouldn’t it be better to drive an Uber in Brooklyn than to get by on welfare in West Virginia?

Yet labor mobility is in a funk. Especially after WWII, millions of Americans with limited resources — southern blacks — moved hundreds of miles from home to take up industrial jobs in the north. At the peak, more than 30 percent of southern-born blacks moved north, from 1920 through the 1960s. Even when technological limitations made long-distance travel extremely onerous, in the late 19 century, we were willing to travel in search of opportunity. In the second half of the 1800s, more than two-thirds of US men over 30 had moved away from their hometowns, and more than a third of those moves were for more than 100 miles.

Nowadays, moving from one state to another has dropped 51 percent from its average in the postwar years, and that number has been decreasing for more than 30 years. Black Americans, once especially adventurous, are now especially immobile. A survey of blacks born between 1952 and 1982 found that 69 percent had remained in the same county and 82 percent stayed in the same state where they were born.

This is especially troubling in context: Studies show major benefits for the children of poor people who move to better-off neighborhoods via, for instance, a program called Moving to Opportunity. If a poor child from a bad neighborhood moved to a middle-class neighborhood at age 8, his expected lifetime income would be $302,000 higher than if he stayed put. Still, the bias toward inertia is so strong that 52 percent of impoverished black families told about Moving to Opportunity declined offers to participate.

One reason people don’t move where the jobs are is because of real-estate prices — which in turn are kept at high levels by regulatory restrictions and NIMBY-ism. In New York City in the 1950s a typical apartment rented for $60 a month, or $530 today if you adjust for inflation. Two researchers found that if you reduced regulations for building new homes in places like New York and San Francisco to the median level, the resulting expanded workforce would increase US GDP by $1.7 trillion. That won’t happen, though: More homes would diminish the property values of existing homeowners.

When we lose the ability to pay for stuff, the poorest and least powerful will be the first and worst hurt.

That locked-in syndrome is a factor in economic stagnation, too: A recent Wells Fargo survey found that white-collar office productivity growth was zero. As the economy was supposedly recovering from the financial crisis, from 2009 to 2014, American median wages fell 4 percent. Men’s median incomes today are actually below 1969 levels. Had we retained our pre-1973 rates of productivity growth, the typical household would earn about $30,000 a year more than it does.

Despite all the hype attached to a few tech companies, far fewer companies are being formed than in the 1980s, and fewer Americans are working for startups. Such new companies are linked with rapid job creation. We’re coming close, Cowen says, to realizing the 1950s cliche (not really true then) of everyone clinging to a job at a handful of huge, soul-crushing companies.

So where is all this heading? “Ultimately peace and stability must be paid for,” writes Cowen. Sluggish growth, diminished productivity, unwillingness to move to a better job and fewer entrepreneurs taking risks to create fortunes adds up to less tax revenue. When we lose the ability to pay for stuff, the poorest and least powerful will be the first and worst hurt. They won’t like it.

The social, economic and political disruption represented by the ascent of President Trump is one of the early warning signs, Cowen says, that the tectonic plates of our society are rumbling. When they start to move, a lot of complacency will be destroyed in the quake.