Capitalization

Q. When should the word “century” be capitalized? I know it would not be capitalized in this case: “It’s not happened in this century.” But what about this: “Were many people rich in the eighteenth century?” or “What did people wear in eighteenth-century Pennsylvania?”

A. Chicago style treats “century” like “day,” “month,” or “year”; we would lowercase it in all the contexts you cite.

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]