Here's a postcard from 1983 by my wife Jeanette. Right after we got married, we bought an old 1972 Ford Econoline camper van and tried to take all the smaller highways across the USA from Los Angeles to the east coast and back. We went to 17 art museums along the way.
We bought a bunch of those blank postcards from the Postal Service, and she used ballpoint pen and watercolor. We sketched everything on postcards as we went, and sent them off to our friends and family.