…well into the 21st century around 70% of Americans reached the top 20% income bracket at some point in their lives. -The Type of Social Mobility That Counts the Most for Psychological Wellbeing Exploring the Problem Space September 11, 2026  

Of course, what goes up tends to go down. But a few years in the higher income brackets can go a long way towards building a meaningful nest egg. And when the good years come to an end, there’s a cushion to soften the fall in income.  

Bottom line: social mobility is alive and well in America. Both upward and downward.  More from AI:

Based on longitudinal research analyzing American income dynamics over the life course, approximately 80% to 90% of American households will reach or surpass the 40th percentile of income at some point in their lives. 

This specific calculation stems from the foundational work on economic mobility and the fluid nature of income by sociologists Mark Rank and Thomas Hirschl. Using the Panel Study of Income Dynamics to track Americans between the ages of 25 and 60, their research reveals that the vast majority of households climb out of the bottom tiers of income during their peak earning years:

  • High Fluidity at the Lower Tiers: Their studies show that while 61.8% of Americans will fall into the bottom 20th percentile (relative poverty) for at least one year, the inverse is also true—the vast majority move upward out of it.

  • The 40th Percentile Cutoff:, the vast majority of Americans (80%–90%) experience enough upward mobility or household change to comfortably cross into the 40th percentile or higher for at least a year. 

Ultimately, because household structures change (e.g., marriage, dual-income setups) and individuals enter their peak career earning years, the life-course likelihood of reaching the 40th percentile of income is nearly universal for the vast majority of Americans.

Unfortunately, these rosy stats can’t hide the fact that up to 20% of the U.S. population remains stuck in the lowest income brackets over their entire lifetime.  

Next:  How to increase upward social mobility among the persistently poor and near-poor. 

Sources:  

Rank MR, Hirschl TA (2015) The Likelihood of Experiencing Relative Poverty over the Life Course. PLoS ONE 10(7): e0133513. https://doi.org/10.1371/journal.pone.0133513  

Hirschl TA, Rank MR (2015) The Life Course Dynamics of Affluence. PLoS ONE 10(1): e0116370. https://doi.org/10.1371/journal.pone.0116370