Property Lines is a column by Curbed senior reporter Patrick Sisson that spotlights real estate trends and hot housing markets across the country. Comments, tips, and suggestions on where Property Lines should head next are welcome at patrick@curbed.com .

It’s graduation season, a time for celebration and optimism for the country’s newly minted college-educated young adults. It’s time to grab that diploma and chase that dream, to move into that first big-city apartment or head cross-country to follow your passion. It’s a standard part of the country’s narrative and mythology.

It’s also one of the aspects of the American dream that’s become less common for today’s young adults. In the U.S., people are staying put like never before.

According to the latest data from the U.S. Census Bureau, the percentage of Americans moving over a one-year period fell to an all-time low of 11.2 percent last year (domestic migration shrunk in half since 1965). The drop is particularly prevalent among millennials. New survey data from the Pew Research Center found that 25- to 35-year-olds are relocating at much lower rates than the previous generation. Last year, 20 percent of millennials moved sometime in the last year. When older generations were the same age as millennials now, they moved at higher rates: Gen X was at 26 percent, as was the generation between 1925 and 1942.

[Source: U.S. Census Bureau]

While there are many factors at play in the country’s decreasing mobility, one thing researchers can agree on is that it’s been declining for decades. This drop has many worried about the housing market, household formation, and economic vitality, as this change has been especially tough on young adults.

What’s puzzling, says Richard Fry, a senior researcher at the Pew Research Center, is that, especially for millennials, it would appear the trend should be leveling out, or even getting better. The job market has improved since the recession, and unemployment is way down. Why are more and more Americans, both economically and literally, feeling stuck?

The housing market is stuck in place

The decline in mobility creates a domino effect on the economy, starting with the American housing market. Many industries that rely on moving and new housing—mortgage lending, home inspections—suffer losses when people decide to stay put.

But the biggest losers may be those those who don’t have homes. Those without a place are left renting, which presents an increasingly heavy burden on young adults. According to Zillow, upward of 45 percent of income in Los Angeles, San Francisco, New York, and Miami for Americans between 22 and 34 goes to rent alone. And with more renting, and more rental demand, prices rise. There’s more incentive for property owners to be landlords; last month, rental payments as a percentage of U.S. GDP hit an all-time high.

Another sign that moving rates are slowing down is that new homes on the market move fast; pent-up demand means buyers eagerly swoop on anything that’s available, leading to bidding wars that drive up prices.

According to data from Moody’s Analytics and First American Financial Corporation, median homeownership tenure—the average time someone stays in their home—just rose to 8.5 years, the highest they’ve seen since they began collecting data in 2008. And right now, especially in hot metro markets like San Francisco and New York, houses move at lightning speed. Redfin found that the average U.S. home went under contract in just 49 days in March, the fastest time on record since Redfin began keeping data in 2010.

“Young buyers are much more stressed when it comes to buying their first home compared to previous generations,” says Ralph McLaughlin, chief economist at Trulia. “The majority of homeowners are baby boomers, who are holding a large amount of the housing stock hostage, so to speak. We need boomers to start moving and retiring to lead to a more competitive, less expensive market that will help millennials get their foot in the door.”

It’s real estate musical chairs, but the tune is a repeat from the recession. Many of today’s issues can be traced to the downturn; the rise in rental housing, which boomed when larger lenders and financial institutions were able to pick up foreclosed homes on the cheap, has removed affordable homeownership options from the market.

“People aren’t in love with their homes, they’re in love with their mortgages.”

Another key factor keeping many older homeowners from leaving is what’s being called the “lock-in effect.” During the bonanza of low interest rates that changed the mortgage market over the last few years, current homeowners became addicted to low monthly payments. If rates rise a few percentage points, current owners have even less of an incentive to move, since any new home requires a new loan, a new rate, and higher monthly payments.

“People aren’t in love with their homes, they’re in love with their mortgages,” says Redfin data scientist Taylor Marr.

The calculus for aspiring homebuyers becomes even crueler in hot markets such as New York City, where a much smaller jump in interest rates would scare off current homeowners. Lock-in has the potential to create a vicious cycle of stagnation, less inventory, and higher prices.

This land isn’t your land

One of the big questions facing millennials seeking a home is “where do I look?” It’s a given that booming cities—such as Nashville, Austin, and Houston—are going to be more affordable than, say, New York and San Francisco. That fact is reflected in part by the population growth in the South. The Census Bureau found that the region had both the greatest number of people moving out (901,000), as well as the largest inflow of people moving into the region (940,000), signs of more dynamism and a flexible housing market.

“In cities such as Austin, Houston, and Nashville, there are more housing starts, more permits, and our data shows inventory is increasing in those areas,” says Marr. “That allows more housing to come onto the market, and really equalizes prices.”

While those regions are assumed to be less expensive due to demand, they’re also less expensive by design. Land-use policies, or a lack of them, has allowed builders and developers to break ground, build new homes, and increase the number of available affordable starter homes. In many expensive markets, tight credit for builders means avoiding affordable projects in favor of high-end housing, Wheatley explains.

“The reason population flows into cities such as Houston and Phoenix are so large is that these cities allow you to build houses, which means you can afford to live there,” says David Schleicher, a Yale Law professor who wrote a research paper—Stuck: The Law and Economics of Residential Stability—about the mobility crisis. “People want to live in San Francisco, but the city doesn’t accommodate their demands.”

Land-use laws, he says, are the single most important part of the story, and the main reason people aren’t moving into the hottest job markets. When supply is artificially constrained in hot housing markets, prices are bid up and only the rich can own property. This causes another cycle that discourages low- and middle-income families from moving to booming urban markets.

“Land use is the elephant in the room,” he says.

Schleicher believes the problem is even more widespread, and has a bigger impact, than many understand. In an increasingly winner-take-all economy, where certain metro areas get the bulk of investment and new business formation, land-use restrictions can lock people out of opportunity. Between 2010 and 2014, for example, 5 percent of metro areas accounted for half of U.S. job growth. Schleicher found that between 1870 and 1970, the average GDP per state was convergent, meaning widespread investment, and a broadening manufacturing economy, led to evenly distributed spoils of economic growth. That has stopped—and reversed sharply—since then.

Limitations on leaving

While Americans overall struggle to afford moving to take advantage of economic opportunity, the impact is felt most strongly among low-income workers. Schleicher believes that mobility, and the ability of Americans of differing income levels to live together in the same community, is foundational to how the country does (or doesn’t) work.

“The American system, especially the welfare system, assumes mobility,” he says. “The tax system, the way we pay for schools, all relies on the rich and poor being in the same community. Not only are people losing out because they can’t move to areas where wages are higher, they’re losing out because those who can move do, and remove important sources of local tax dollars. If you’re poor, you’re getting screwed in a number of different ways.”

Increasingly, he says, less wealthy Americans face new limitations on leaving. One of the more prevalent, and less commented upon, is the growth in occupational licensing fees and requirements across the country. In 1950, these regulations impacted 5 percent of jobs. Now, they impact anywhere from a quarter to a third of Americans, touching more workers than labor unions. Combined with the increasing prevalence of non-compete clauses, switching jobs has suddenly become more difficult.

“It’s an indirect tax for moving across state lines,” says Marr.

Consider the case of a barber and a lawyer moving from Mississippi to San Francisco. The lawyer, who will have to pay for exams and other relocation expenses, will more than make up the difference in a market where he or she is making a lot more money. For a barber, who likely lacks the same capital, a move and new licensing fees and requirements may not be worth it, since the smaller rise in income may not offset the cost of the move.

“If you’re poor, you’re getting screwed in a number of different ways.”

And, not surprisingly, lower-income millennials are also feeling increased pressure. The Census Bureau estimates that, even with a full-time job, young adults earn on average $2,000 less in real dollars than their peers made in 1980. White House data also suggests more young adults undergo long periods of unemployment and suffer low rates of workforce participation.

These market realities, combined with rising rents, create a sense of being stuck. Schleicher says that many have it wrong with they look at millennials, see lower rates of household formation and homeownership, and assume they’re different, or that they’re just “on their couches playing video games.” In terms of what millennials aspire to, they’re fairly similar to previous generations. They may be playing the same game, but it appears the goalposts have been moved.