Alan Brinkley, a historian of the Depression, added: “This is not the New Deal, but it’s a significant series of achievements. And given the difficulty of getting anything done under the gridlock of Congress, it’s pretty surprising.”

The last 16 months seem most similar in scope to three other periods in the last 80 years. After World War II, the federal government helped build the modern middle class with the G.I. Bill, housing subsidies, the highway system and incentives for employers to offer health insurance. The 1960s — mostly under Mr. Johnson, but also Richard Nixon — brought civil rights legislation, Medicare, Medicaid and environmental laws. Then Mr. Reagan ushered in a period that continued, more or less, until 2008: tax cuts, less regulation and other attempts to unleash the competitive forces of the market.

Mr. Obama has been trying to reverse the Reagan thrust in some important ways. Although the Reagan administration did not shrink the size of the federal government, it changed the ways that Washington collected and spent its money, by reducing taxes on the affluent, cutting some social programs and increasing military spending.

These policies ended up magnifying income inequality, which was already rising for other reasons. Since 1980, median household income has risen only 30 percent, adjusted for inflation, while average incomes at the top have tripled or quadrupled. Every major piece of the Obama agenda is meant, in part, to push back against inequality. Government may grow, but the bigger change will be how the government is spending its money.

The health bill expanded insurance coverage largely for middle-class and poor families and paid some of the bill by taxing households making more than $250,000 a year. Attached to the final health bill were also education provisions that cut subsidies to banks making student loans, and used much of the money for college financial aid instead.

The financial regulation bill, meanwhile, would take several steps likely to reduce Wall Street’s profits — and Wall Street has created more multimillionaires in recent decades than any other industry. To take one example, certain trades would be forced onto open exchanges. This would hurt financial firms’ ability to act as a middleman, much as Expedia and other travel Web sites have hurt travel agents.

For all these differences, though, there are also ways that Mr. Obama and today’s Democrats have accepted, and are even furthering, the Reagan project. They are not trying to raise tax rates on the affluent to anywhere near their pre-1981 levels. Their health bill created new private insurance markets, rather than expanding Medicare.