The Westcott company was established in 1874 by Captain J.W. Westcott, who first ferried supplies, and by 1895 the mail, to passing ships via rowboat.
The J.W. Wescott II serves to deliver mail to other vessels, and also provides a pilot boat service to ferry pilots to and from other vessels.
The postal station is located just south of the Ambassador Bridge along the western shore of the Detroit River. The ZIP Code 48222 is exclusive to the floating post office and its ship addressees.
Any mail addressed to members of ships' crews that pass through the Detroit River can have mail delivered to them via the J.W. Westcott II, by addressing it to the vessal name, Marine Post Office, Detroit, MI.