There isn&#x27;t a lot of data about this for the US. There is, however, writing on the subject that should be of interest:<p><a href="http:&#x2F;&#x2F;www.economist.com&#x2F;blogs&#x2F;buttonwood&#x2F;2014&#x2F;03&#x2F;inequality" rel="nofollow">http:&#x2F;&#x2F;www.economist.com&#x2F;blogs&#x2F;buttonwood&#x2F;2014&#x2F;03&#x2F;inequality</a><p>&quot;Whenever the rate of return on capital is significantly and durably higher than the growth rate of the economy, it is all but inevitable that inheritance (of fortunes accumulated in the past) predominates over saving (wealth accumulated in the present).... Wealth originating in the past automatically grows more rapidly, even without labour, than wealth stemming from work, which can be saved.&quot;<p>Per the article, there is extensive data available from France on wealth, and in France inheritances as a proportion of income went from 24% in 1900 to 4% in 1950, but has increased to 11% today. If that proportion regressed to 1900 levels, 90% of wealth would be inherited by mid-century.<p>IMO, we&#x27;re at the start of this process in the US, as tax-insulated retirement schemes like Roth accounts, trusts and other mechanisms allow for long-term&#x2F;generational transfer of wealth without taxation.