…consider what we know from previous studies of trends in intergenerational income mobility. The bulk of the existing research shows either that mobility has increased over the long run or that it has changed little in either direction. That includes both studies that I know of examining changes in upward mobility from the bottom. It also includes six studies using measures of mobility not confined to movement up from the bottom; these find either no change or rising mobility. In contrast, only two papers find a fall in mobility, each using non-directional measures. Notably, one of them shows an uptick in the mobility of the most recent two birth cohorts it examined, leaving in doubt the question of whether the longer-term decline it found would have persisted had the authors had more recent data. The other study finds somewhat mixed evidence, depending on the data source and whether children of single parents are included.
Of course this doesn’t mean mobility is “high enough.” Scott also will be publishing a more detailed explication of these results with Brookings.