This trip was another "weekend adventure" with my daughter. I had (apparently) been to the grave of William Burnham Woods the day before, so I must've still been in "cemetery mode."
Day is buried in the cemetery that abuts the McKinley Monument. His grave was absurdly difficult to find. I went up and down that place trying to find it, but eventually found it.
Fun note: Day was born in Ravenna OH, just one town over from my hometown of Kent OH.