Inequality in family incomes increased in each of the three decades from 1988 to 2018 as income grew fastest for those with higher incomes.
Key Points

In 2018, the average income for the highest 20% of families was 3.3 times as high as that for the middle 20% ($261,760 vs. $78,970 in 2018 dollars). It was 2.6 times as high in 1988 ($173,830 vs. $65,970).

In 2018, the average income for the middle 20% of families was 3.9 times as high as that for the lowest 20% ($78,970 vs. $20,380). It was 3.6 times as high in 1988 ($65,970 vs. $18,200).

In 2018, median family income of families headed by individuals ages 45 to 54—the age bracket of most parents of traditional age college students—was 27% higher than the overall median ($100,180 compared with $78,650).

In 2018, median incomes of black and Hispanic families were 59% and 62%, respectively, of the median for white families. The median income of Asian families was 13% higher than the median for white families.
 In 2018, the $121,060 median family income of families headed by a fouryear college graduate was more than twice the median for families headed by a high school graduate.
Figure 20A: Percentage Change in InflationAdjusted Mean Family Income by Quintile, 1988 to 1998, 1998 to 2008, and 2008 to 2018
Figure 20B: Median Family Income by Selected Characteristics, 2018
_{SOURCES: U.S. Census Bureau, Current Population Survey, 2018 Annual Social and Economic Supplement, Table F1, Table F3, Table F5, and FINC01; calculations by the authors.}
Also Important
 The share of all income going to the 20% of families with the lowest incomes has steadily declined, from 4.6% in 1988 to 4.2% in 1998, to 4.0% in 2008, and to 3.8% in 2018. The share of income going to the top 5% of families rose from 17.2% in 1988 to 20.7% in 1998. It was 20.5% in 2008 and 21.6% in 2018. (U.S. Census Bureau, Table F2)
 Average published tuition and fees for instate students attending public fouryear colleges rose by $6,870 (in 2018 dollars) over this 30year period—53% of the increase in income ($13,000) of the middle 20% of families and 8% of the increase in income ($87,930) of the 20% of families with the highest incomes. (Online Table 2; calculations by the authors)