The number of married couples with children under age 18 fell by 1 million between 2010 and 2016, according to Census Bureau data, the only household type to decline during those years. Behind the decline is the postponement of marriage and childbearing by young adults.
Married couples with children under age 18
2016: 25.1 million (20% of households)
2010: 26.1 million (22% of households)
Source: Census Bureau, Current Population Survey