Many U.S. statistics on education are collected and published (print and online) by federal and state government agencies. A few suggested sites in the areas of education (specifically) and general statistics and demographics (national and international) are listed below.
See an enormous collection of Statistics at this guide: http://library.knox.edu/statistics
Childstats.gov
Contains statistical information detailing the wellbeing of children in the United States.
FedStats
Contains statistical information from over 100 U.S. Federal Government agencies. Subjects covered include economic and population trends, education, health care costs, aviation safety, foreign trade, energy use, farm production, and more.
Historical Statistics of the United States
Contains statistical information on every quantifiable dimension of American history, including population, work and welfare, economic structure and performance, governance, and international relations from colonial times to the present.
International Statistical Agencies
Contains links to many nations' statistical bureaus. Most of the data provided is in English as well as the language of origin.
National Center for Education Statistics
Contains statistical information on all levels of U.S. education - early childhood, elementary, secondary, and postsecondary.
The United States Census Bureau is the place to go for current census data. The decennial census contains demographic information about the United States population. current data is based on the 2010 census. The site also provides access to earlier census data.