About one-third of U.S. children are living with an unmarried parent

 The type of family arrangement a child lives in is associated with a household’s economic situation. A recent Pew Research Center analysis found that 30% of solo mothers and their families are living in poverty compared with 17% of solo father families and 16% of families headed by a cohabiting couple. In comparison, 8% of married couple families are living below the poverty line.

https://www.pewresearch.org/short-reads/2018/04/27/about-one-third-of-u-s-children-are-living-with-an-unmarried-parent/