Statistic:

Of the 6 million grandparents who live with their grandchildren, 2.45 million of them have the primary responsibility of caring for the grandchildren (United States Census Bureau, 2007).

Source:

United States Census Bureau (2007). Selected Characteristics of Grandparents Living With Grandchildren for the United States, States, District of Columbia, and Puerto Rico: 2005-2007. Retrieved on June 29, 2009, http://www.gu.org/documents/A0/Grandparents%20Living%20with%20Grandchildren%202005-2007.pdf

Description of Sample:

“This report looks at both grandchildren living in grandparent’s home and
grandparents living in grandchildren’s home. The American Community Survey universe is limited to the household population and excludes the population living in institutions, college dormitories, and other group quarters.”

Scope of Study:

National