From the article:

Threshold income or consumption per month for each decile, United States,1963 to 2024

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• This data comes from the World Bank's Poverty and Inequality Platform, which is based on a large collection of national survey data. To achieve wide coverage, it pools data from two kinds of surveys. For high-income countries, the data measures people's incomes after taxes and benefits. For most low- and middle-income countries, it instead measures their consumption — a different but closely related measure.