Yep. My map shows the percent of students hit in 2008. It was at least 1.0% for each of the shaded states, 7.5 % for Mississippi.
Interesting to see how much the practice has faded in the peripheral states in the past few years.
I made this map a few years ago but based it solely off of the county level (since I couldn't ever find a national school district map and the data-set I was using was based off of counties even in some states with multiple school districts per county).
It's dropped significantly in places like KY, NC and the Mountain West. What is even more unfortunate is that in many cases, the children who are punished this way are disproportionately mentally handicapped or minorities. I remember how big the numbers from 2009-11 were in Robeson, NC, for instance, and it doesn't shock me to see it's the only remaining county in NC where the practice was still being used in the latter map.