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.