According to NCES’s Common Core of Data for 2009-10, here are a few interesting statistics on which I’ll try to follow-up as time permits:

Of 17,916 school districts nationwide, 16,643 (92.9%) report on librarian staffing (including zeroes). Of those reporting districts:

• 10,678 (64.2%) report non-zeroes (i.e., anything, as little as .01 FTE for a whole district);
• 10,063 (60.5%) report at least .50 FTE of librarian staffing; and
• 9,034 (only 54.3%–of districts, mind you), report at least 1 FTE or more of librarian staffing.

Unfortunately, CCD does not specify state certification of librarians, but then it doesn’t do that for teachers or administrators either. For what it’s worth.

The more alarming perspective on this data: 35.8% of districts that report about school librarians report having none.