America used to be Sweden: According to new research, the America of the Founding Fathers was ‘‘more egalitarian than anywhere else in the measurable world.’’

That’s an important finding, and one that will surprise most Americans today. Both inequality and American exceptionalism are high on the national political agenda. One idea that brings those issues together is the belief that Americans have an exceptional cultural tolerance for income inequality. Unlike Europeans, the thinking goes, most Americans are confident that they are ‘‘soon to be rich.’’ As a result, the conventional wisdom has it, Americans in the middle look up to their 1 percent and are loath to tax them.

But historical research by the economists Peter H. Lindert and Jeffrey G. Williamson shows that when it comes to inequality, this American exceptionalism is an inversion of the conditions that prevailed at the time of American Revolution. In that era, which is so often invoked in today’s political and social battles, America was the world’s most egalitarian society – and proud to be so.

‘‘There has been an absolute reversal,’’ Lindert told me. ‘‘Compared to any other country from which we have data, America in that era was more equal. Today, the Americans are the outliers in the other direction.’’

Nowadays, we think of the postwar era as a halcyon time for the U.S. middle class. But it turns out that, in relative terms, colonial America, too, was a great country for the 99 percent, particularly when compared with the folks back in the old country.

‘‘Americans who were free were very well-off, and better off than their counterparts in the mother country,’’ Lindert said. ‘‘Every kind of person by occupation was better off than their counterpart by occupation. The carpenters, the shopkeepers and so forth all had a slightly better income than in the mother country.’’

Slavery is America’s original sin and was the great global injustice of that age. But on a purely economic basis, even when slaves are included in the calculation of inequality, America comes out as the most egalitarian.

‘‘If one includes slaves in the overall income distribution, the American colonies in 1774 were still the most equal in their distribution of income among households, though by a finer margin,’’ Lindert said.

Members of only one group fared better in Europe than their peers in the colonies – the people at the very top.

‘‘The Duke of Bedford had no counterpart in America,’’ Lindert said. ‘‘Even the richest Charleston slave owner could not match the wealth of the landed aristocracy.’’ Indeed, England’s 1 percent were so rich that the country’s average national income was nearly as high as that of the colonies, despite the markedly greater prosperity of what today we might call the American middle class.

Today, the opposite is true, Lindert said: ‘‘The rest of the world can’t come close to the 1 percent in America.’’

This portrait of colonial America as the world’s great egalitarian exception would probably come as a surprise to most Yanks today. But though Lindert and Williamson provide us with new data, the portrait they paint fits with contemporary accounts.

In a letter he wrote from Monticello in 1814, Thomas Jefferson applauded America’s economic equality. ‘‘We have no paupers,’’ he wrote to Thomas Cooper, an Anglo-American polymath and frequent Jefferson correspondent. ‘‘The great mass of our population is of laborers; our rich, who can live without labor, either manual or professional, being few, and of moderate wealth. Most of the laboring class possess property, cultivate their own lands, have families, and from the demand for their labor are enabled to exact from the rich and the competent such prices as enable them to be fed abundantly, clothed above mere decency, to labor moderately and raise their families.’’

By contrast, Jefferson believed, as the Lindert and Williamson research confirms, that members of America’s 1 percent were worse off than their European counterparts:

‘‘The wealthy, on the other hand, and those at their ease, know nothing of what the Europeans call luxury. They have only somewhat more of the comforts and decencies of life than those who furnish them.’’

Interestingly, particularly in view of today’s inequality wars, Jefferson didn’t pull his punches about which social order was preferable. ‘‘Can any condition of society be more desirable than this?’’ he opined about egalitarian America, and then did a little calculation showing that the overall happiness of Americans far outweighed that of the English, for whom ‘‘happiness is the lot of the aristocracy only.’’

It wasn’t just the Americans who perceived their society to be more economically equal than the Old World. Foreign visitors noticed, too. After his famous journey to America in the 19th century, Alexis de Tocqueville returned home to France to report that ‘‘nothing struck me more forcibly than the general equality of conditions among people.’’

But what was obvious just before the Revolution has been largely forgotten today. ‘‘It was known by them at the time,’’ Lindert said. ‘‘Now we as a society may have lost sight of that, because we didn’t have the numbers to remind us.’’

Thanks to Lindert and Williamson, we now do. Their historical work makes a particularly important contribution to the current debate because, as chance would have it, those who argue that inequality is as American as apple pie tend also to hold the views of the Founders in particularly high regard.

‘‘I see it as a puzzle,’’ Lindert said. ‘‘Those of us who insist that inequality is fine would also invoke a Founding Fathers’ society for which it was not true.’’

Equality, not just of opportunity but also of outcome, turns out to be one of the features that really did make the United States exceptional in the age when the country was born. That startling fact is worth bearing in mind as Americans struggle to figure out how to remain exceptional in an altogether more complicated era.