# From 1928 to the 1940s, the richest tenth's share of America's income fell and fell.

- Series: [The Better Guess](https://miu.fm/thebetterguess.md)
- Premieres: 2026-11-04
- Page: https://miu.fm/thebetterguess/from-1928-to-the-1940s-the-richest-tenth-s-share-of-america

## Story

From 1928 to the 1940s, the richest tenth's share of America's income fell and fell. Down, flat or back up next?

In December 1954 the economist Simon Kuznets told the American Economic Association that inequality had been falling in America and Britain: the richest fifth of US families had gone from 55 percent of income in 1929 to 44 percent in the late 1940s. He guessed at a long swing, inequality rising as countries industrialise and then falling, and he warned that his paper was "perhaps 5 per cent empirical information and 95 per cent speculation". The idea became famous anyway, as the Kuznets curve.

Fifty years later Thomas Piketty and Emmanuel Saez stretched the same US tax records out to the present. The top tenth's share was about half in 1928, about a third from the mid-1940s to 1980, and back to about half by 2012. Kuznets had been looking at the downhill half of a U. Piketty argues the fall came above all from two world wars and the policies after them. His long-run explanation is r > g: wealth earning 4 to 5 percent a year while the economy grows 1 to 1.5. A century at 5 percent multiplies money about 131 times; at 1.5 percent, about 4.4 (our arithmetic).

Others dispute it. Acemoglu and Robinson find the gap between r and g does not explain top income shares; Rognlie finds the rise in capital's share is mostly housing; Auten and Splinter find a much smaller recent rise once missing income, taxes and transfers are counted. The lesson that survives is simpler: zoom out before you forecast.

The chart is the US top 10 % share of pre-tax income including capital gains, from Piketty and Saez's series as updated by Saez in 2026, drawn as a smooth line through seven published years. The long swing is our sketch of Kuznets's idea; his paper had no chart.

So, which way did you draw it?

Sources: Simon Kuznets, "Economic Growth and Income Inequality", American Economic Review 45, 1955; Thomas Piketty and Emmanuel Saez, "Income Inequality in the United States, 1913-1998", Quarterly Journal of Economics 118, 2003, and Emmanuel Saez's updated tables, 2026; Thomas Piketty, Capital in the Twenty-First Century, 2014 (French original 2013); Daron Acemoglu and James Robinson, Journal of Economic Perspectives 29, 2015; Matthew Rognlie, Brookings Papers on Economic Activity, 2015; Gerald Auten and David Splinter, Journal of Political Economy 132, 2024.
Sounds: our own, made in code (earshot, CC0).

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