According to the AFCARS Report (Adoption and Foster Care Analysis and Reporting System Report), there were 510,000 in the foster care system on September 30, 2006 in the United States.
SOURCE:
The Adoption and Foster Care Analysis and Reporting System (AFCARS) has provided the following information. This data was submitted for the FY 2006, which runs from 10/1/05 through 9/30/06. This data can give us an idea of how a typical year looks for foster care and adoption. This data does not mean that a child will definitely be in your home for the amount of time shown in this FAQ, but can give us an idea of the time range.

