U.S. Income Inequality: Gini Coefficient and Income Shares by Quintile, 2024

Income inequality in the United States remains a critical indicator of the nation’s economic health and social structure. By analyzing the distribution of money income, economists and policymakers can determine how wealth is concentrated among the population and whether economic growth is being shared across different social strata. The most recent data for 2024 reveals a persistent gap between the highest and lowest earners, characterized by a high Gini Index and a significant concentration of aggregate income within the top twenty percent of households.

Key Numbers

• Gini Index of Income Inequality: 0.488
• Highest Quintile Income Share: 52.2%
• Lowest Quintile Income Share: 3.1%
• 90th/10th Percentile Ratio: 12.61
• 50th/10th Percentile Ratio: 4.21
• 90th/50th Percentile Ratio: 3.00
• Fourth Quintile Income Share: 22.6%
• Third Quintile Income Share: 13.9%

Explanation

Income inequality refers to the extent to which income is distributed unevenly among a population. In the United States, this is primarily measured using money income, which includes wages, salaries, self-employment income, and other cash transfers, but does not account for non-cash benefits or taxes. When income is highly concentrated at the top, the gap between the wealthiest and the poorest citizens widens, often impacting social mobility and economic stability.

To quantify this disparity, the U.S. Census Bureau employs several metrics. The Gini Index is the most widely recognized, providing a single number that represents the degree of inequality. Additionally, income quintiles divide the population into five equal groups (20% each), allowing analysts to see exactly what percentage of the total national income is captured by the poorest 20% versus the wealthiest 20%.

Definition

Income inequality is the unequal distribution of household or individual income across the various participants in an economy. In the context of the U.S. Census Bureau’s P-60 reports, this is specifically measured using Money Income. This measure captures the actual cash flow into a household before taxes and without adjusting for the number of people in the household (unlike equivalence-adjusted income). The goal is to provide a snapshot of the raw financial disparity existing within the U.S. population.

Historical Data

The trajectory of income inequality in the U.S. has shown a general upward trend since the late 1960s. In 1967, the distribution of income was more balanced than it is today. Over the decades, the share of income held by the highest quintile has grown, while the share held by the lowest quintile has shrunk.

Trend Chart

While a visual chart cannot be rendered here, the data from the Census Bureau’s Figure 3 illustrates a clear climb in the Gini Index from 1967 through 2024. The 90th/10th percentile ratio, which compares the income of the top 10% to the bottom 10%, has risen significantly, reaching 12.61 in 2024. This indicates that the top 10% of earners make more than twelve times the income of the bottom 10%.

Income Shares by Quintile

The division of aggregate income by quintile provides a stark look at the concentration of wealth. The total national income is split into five groups, each containing 20% of the households. The 2024 data shows a heavy skew toward the top.

• Highest Quintile (Top 20%): 52.2% of all income.
• Fourth Quintile: 22.6% of all income.
• Third Quintile (Middle 20%): 13.9% of all income.
• Second Quintile: 8.2% of all income.
• Lowest Quintile (Bottom 20%): 3.1% of all income.

This means the top 20% of households earn more than the bottom 80% combined (52.2% vs 47.8%).

Why It Matters

Income inequality is more than just a statistical curiosity; it has profound implications for the U.S. economy and society. High levels of inequality can lead to several systemic issues:

• Reduced Social Mobility: When the gap between the bottom and middle quintiles is vast, it becomes harder for individuals born into low-income households to move up the economic ladder.
• Economic Volatility: Excessive concentration of wealth can lead to under-consumption among the lower and middle classes, who typically have a higher marginal propensity to consume.
• Political Influence: Extreme income disparity often correlates with a concentration of political power, potentially skewing policy decisions toward the interests of the highest earners.

Methodology

The data is derived from the Current Population Survey (CPS), specifically the Annual Social and Economic Supplement (ASEC). The Census Bureau collects detailed information on household income, including earnings, social security, and investment income. To ensure comparability over time, the Bureau adjusts historical data for inflation using 2024 dollars. The Gini Index is calculated based on the Lorenz curve, which plots the cumulative percentage of total income received against the cumulative number of recipients, ranging from 0 (perfect equality) to 1 (perfect inequality).

Limitations of the Data

While the Census Bureau’s data is the gold standard for official statistics, it has known limitations:

The use of Money Income may understate the true extent of inequality because it often fails to capture the full extent of high-end capital gains and complex investment vehicles used by the ultra-wealthy. Additionally, it does not account for non-cash government transfers (like food stamps) which can mitigate the impact of low money income on the poorest households.

Furthermore, because the data relies on self-reporting via surveys, there is a possibility of under-reporting among both the very low-income and very high-income populations.

Source & Data Date

The primary source for this data is the U.S. Census Bureau, specifically the report Income in the United States: 2024 (Report Number P60-286), released in September 2025. The statistics cover the 2024 calendar year, with historical comparisons dating back to 1967.