Periods and commas in relation to closing quotation marks
“Periods and commas precede closing quotation marks, whether double or single. (An apostrophe at the end of a word should never be confused with a closing single quotation mark.) This is a traditional style, in use in the United States well before the first edition of this manual (1906).”
— The Chicago Manual of Style, 17th ed. ¶ 6.9
Other punctuation in relation to closing quotation marks
Colons and semicolons—unlike periods and commas—follow closing quotation marks; question marks and exclamation points follow closing quotation marks unless they belong within the quoted matter.
— The Chicago Manual of Style, 17th ed. ¶ 6.10