I'm talking, of course, about homeownership.
In 2016 the average net worth of a family who owned their own home stood at $231,400, according the Survey of Consumer Finances. Renters, by contrast, had a net worth of just $5,200.
That's nearly a 45-fold difference, and the gap is getting bigger. From 2013 to 2016, the average net worth of homeowners rose by 15 percent. For renters it actually fell, by 5 percent.
In inflation-adjusted terms, the average net worth of renters is at its lowest level since 1989.
It's no secret that homeownership is the engine of American middle-class wealth. Owning a home is like having a savings plan that you're forced to contribute to every month. After interest, the money you pay on your mortgage accrues directly to you.
This isn't to say that homeownership is a magic ticket to prosperity. Financially speaking you have to be in pretty healthy shape to afford a house to begin with: You need to have saved up money to afford a down payment, as well has have enough coming in every month to pay the mortgage. Try to purchase a house without these things and bad things happen, as we saw in the 2007 housing crisis.
So the relationship between wealth and homeownership is something of a circular one. You have to have wealth to buy a house, but you have to have a house to accrue wealth.
As home prices rise and middle-class incomes stagnate, it becomes harder and harder to break into that cycle of wealth. Back in 1965, for instance, the median family made $6,882 while the median new home sold for around $20,000, according to the Census Bureau. A house cost less than three years' salary, in other words.
Last year, on the other hand, the median household income was $59,039 while the median new home sold for a whopping $307,800. The price of a house is now more than five times the typical annual salary.
Some of that growing gap is explained by the fact that we're getting bigger homes for our money nowadays. But for people priced out of the housing market, that means it's harder than ever to grow their net worth.