https://www.fcd-us.org/trends-in-state-funded-preschool-programs-survey-findings-from-2001-2002-to-2011-2012/
For the last decade, NIEER has tracked the policies of state-funded preschool programs through its State Preschool Yearbook. The report, which started with the 2001-2002 school year, provides annual data on enrollment, policies relating to access and quality, and expenditures through the 2011-2012 school year. The goal of the Yearbook is to improve the public’s knowledge and understanding of state efforts to educate young children.
The data document tremendous change in state pre-K over the decade, some of it good, and some not. The most dramatic change has been that states now serve nearly 30 percent of 4-year-olds, slightly more than 30 percent when preschool special education is included. State pre-K now serves more than twice as many 4-year-olds as Head Start and more children than Head Start serves at all ages. This report details major trends in state pre-K over the last decade and discusses their implications.