In this answer, it is suggested that the Chicago Manual of Style (CMoS) specifies whether spaces precede a footnote indicator. The main three choices I see being:
I'd like to know where in the CMoS it specifies which style to use and which of the three it suggests or discusses (I believe it is without space, but would like to confirm with a cite).
Note that Wikipedia has standardized on no space or a hair space.
Chicago Manual of Style features many examples of footnotes without spaces, and says nothing to contradict that practice. Also, from over a decade of experience with Chicago, I understand footnotes should follow directly after what they note without a space.
All of these examples of usage are in 14.26: Placement of note number in the online version of the Chicago Manual of Style, 17th edition. I have preserved the spacing exactly, only adding some superscript code (<sup></sup>) so it appears correctly in StackExchange:
“This,” wrote George Templeton Strong, “is what our tailors can do.”1
It was the hour of “national paths” toward socialism;9 but that expression, which turned out to be temporary, was more an incantation than a discovery.
The bias was apparent in the Shotwell series3—and it must be remembered that Shotwell was a student of Robinson’s.
[...]
(In an earlier book he had said quite the opposite.)2
Men and their unions, as they entered industrial work, negotiated two things: young women would be laid off once they married (the commonly acknowledged “marriage bar”1), and men would be paid a “family wage.”
The Chicago Manual of Style states that:
A note number should be placed at the end of a sentence or at the end of a clause. The number follows any punctuation mark, except for the dash, which it precedes. It follows a closing parenthesis.
That's section 16.30 in CMoS, 15th edition.
Seems pretty definitive to me.
