With the large majority of U.S. mothers in the labor force and a steady decline in the real earnings of all workers over recent decades, families are increasingly relying on mothers’ earnings for economic stability. In the United States, half of all households with children under 18 have a breadwinner mother, who is either a single mother who heads a household, irrespective of earnings, or a married mother who provides at least 40 percent of the couple’s joint earnings.