The National Institute for Early Education Research produces valuable tools annually for evaluating the state of pre-kindergarten in the U.S. Their access and quality data, updated in each State Preschool Yearbook (PDF), show the current status of pre-k and the prospects for its future in every state and the District of Columbia.
Pre-K Access (PDF) – See the percent of 4 year olds served in state pre-k nationwide.
Pre-K Quality (PDF) – See the number of state pre-k programs meeting benchmarks 2002-2009