Subscribe to The Chicago Manual of Style Online
Q. Hello, I’m looking for clarification for CMOS 10.33. Are you recommending 123 MAIN ST STE 456 for envelopes but 123 Main St., Ste. 456 for running text, etc.? (And if capitalizing the envelopes, would the entire address be capitalized?)
A. As we say at CMOS 10.33, spell out the terms in running text: I live at 123 Main Street, Suite 456. (Please see 10.35 as well). As for addressing envelopes, CMOS does not presume to override US Postal Service instructions. If you want your mail delivered, you’d better abandon Chicago style.