Recent research on United States levels and trends in income inequality vary substantially in how they
measure income. Piketty and Saez (2003) examine market income of tax units based on IRS tax return
data, DeNavas-Walt, Proctor, and Smith (2012) and most CPS-based research uses pre-tax, post-transfer
cash income of households, while the CBO (2012) uses both data sets and focuses on household size-adjusted
comprehensive income of persons, including taxable realized capital gains. This paper provides a crosswalk
of income growth across these common income measures using a unified data set. It then uses a more
consistent Haig-Simons income definition approach to comprehensive income by incorporating yearly-accrued
capital gains to measure yearly changes in wealth rather than focusing solely on the realized taxable
capital gains that appear in IRS tax return data. Doing so dramatically reduces the observed growth
in income inequality across the distribution, but most especially the rise in top-end income since 1989.