This advertisement appeared in the Green Bay Press-Gazette in February 1976.

I don't know if the ad was used at other times or in other publications.  The February 1976 Press-Gazette ad was the only time I saw it used.

Here are some enlarged details from the ad.

• Car Ferries - Ann Arbor and Chesapeake & Ohio car ferries depart from Kewaunee.
• Cartoon Figure - Emphasizing that it takes only four hours to cross Lake Michigan by car ferry.