In the 1930s and ’40s, the term appeared occasionally in advertisements for intellectual products: plays, books and church sermons, book reviews and high-minded articles. During these years, it rarely, if ever, referred to business success or homeownership.

By 1950, shortly after World War II and the triumph against fascism, it was still about freedom and equality. In a book published in 1954, Peter Marshall, former chaplain of the United States Senate, defined the American Dream with spiritually resounding words: “Religious liberty to worship God according to the dictates of one’s own conscience and equal opportunity for all men,” he said, “are the twin pillars of the American Dream.”

The term began to be used extensively in the 1960s. It may have owed its growing power to Martin Luther King’s “I Have a Dream” speech in 1963, in which he spoke of a vision that was “deeply rooted in the American Dream.” He said he dreamed of the disappearance of prejudice and a rise in community spirit, and certainly made no mention of deregulation or mortgage subsidies.

But as the term became more commonplace, its connection with notions of equality and community weakened. In the 1970s and ’80s, home builders used it extensively in advertisements, perhaps to make conspicuous consumption seem patriotic.

Thanks in part to the deluge of advertisements, many people came to associate the American Dream with homeownership, with some unfortunate results. Increasing home sales became public policy. In 2003, President George W. Bush signed the American Dream Downpayment Act, subsidizing home purchases during a period in which a housing bubble — the one that would lead to the 2008-9 financial crisis — was already growing at a 10 percent annual rate, according to the S.&P. Corelogic Case-Shiller U.S. National Home Price index (which I helped to create).

This year, Forbes Magazine started what it calls the “American Dream Index.” It is based on seven statistical measures of material prosperity: bankruptcies, building permits, entrepreneurship, goods-producing employment, labor participation rate, layoffs and unemployment claims. This kind of characterization is commonplace today, and very different from the original spirit of the American dream.

One thing is clear: Bringing back the fevered housing dream of a decade ago would not be in the public interest. In “House Lust: America’s Obsession With Our Homes,” published in 2008, Daniel McGinn marveled at the craving for housing in that era: “In many neighborhoods, if you’d judged the nation’s interests by its backyard-barbecue conversation — settings where subjects like war, death, and politics are risky conversational gambits — a lot of people find homes to be more compelling than any geopolitical struggle.”