Over the long run of history, young Americans as they have grown more affluent have moved out of their parents’ households. A century ago, that meant when they got married, but marriage was postponed until a man could support a family: The median age for marriage in 1890 was 26 for men, and in 1900 15 percent of men and 10 percent of women over 30 had never been married — far higher than today. Households typically included bachelor uncles and maiden aunts, with children doubled or tripled up in bedrooms.
This changed slowly in the early 20th century, but change was halted by the Depression of the 1930s. Marriages were postponed or put off forever; young people were content to stay put with their parents. The sudden and unexpected prosperity of the post-World War II years liberated young Americans from the parental home. Veterans and their wives poured into the suburbs, as the median age for marriage for men fell to an all-time low of 22 in the late 1950s; in those years most American women were already married when they turned 21 and became eligible to vote.
These postwar young marrieds moved out from their parents but lived in what we would regard as cramped quarters; tract houses in Levittown measured just 750 square feet. Advancing prosperity and changed mores in the 1960s and 1970s allowed other arrangements. Americans increasingly went to college and got married later; many unmarried couples started living together in college towns, garden apartments and even suburban houses. Staying with the old folks became unthinkable.
The quarter-century of low-inflation economic growth from 1983 to 2008 gave young Americans ever more choices. Good starting salaries for college graduates enabled young people to live in a style the postwar Levittowners would have considered lavish. New housing averaged 2,000 square feet by 1990 and 2,500 square feet by 2007.
But those spacious houses and apartments came with an undisclosed price: The housing bubble burst in 2007 and 2008, and the economy tanked. Suddenly college graduates, with no job offers and not enough money to afford a studio, found themselves making the same choice their as yet unmarried ancestors found themselves forced to make: living with Mom and Dad.
