Facts and Figures About Oregon Schools provides a nice synopsis of current state, district and student data. Statewide Assessment Results can be found on this site as well. There is current as well as historical data. A good resource to bookmark. The Oregon Department of Education produced this statistical table on net enrollment data for Oregon schools.
Data is available for state level only and arranged chronologically for each grade level.
U.S. figures are appended for comparison. There is detailed data here not readily available elsewhere. Choose your state from the map and then search by school district or by county. The University of Michigan Documents Center publishes this well-maintained comprehensive set of links to statistical resources. A new section of statistical reports on school violence was recently added.