just their paychecks, not other income—have been flat since the end of the recession in June 2009 thanks to a lethargic economy, businesses restraining pay and globalization. That is muffling consumer spending and holding back the recovery.

But new research by two economists, Richard Burkhauser of Cornell University and Jeff Larrimore of Congress’s Joint Committee on Taxation, suggests things may get even worse in coming years—thanks to two basic population trends. After supporting the economy during their peak earning years, America’s Baby Boomers are starting to retire, which will mean higher numbers of lower-income older individuals. Second, the researchers argue, relatively high-earning whites are over time being replaced by minority workers, especially Hispanics, who tend to make less money.

Burkhauser and Larrimore project these two factors will reduce growth in median incomes by about 0.5% per year through 2030.