Postcards have been published in various formats of the physical card, with most fitting within the large sized shoeboxes used to house this collection.

Jumbo postcards are found listed by the image identification within Series III, though they are housed in Box 6 due to the larger physical format.

Postcards images have occasionally been published by the common postcard companies listed here in a unique physical form other than the card. For those few cases where examples of the unique formats exist in the collection, they are documented in the separate series. One example of a special format found in the collection are postcard images commonly used by Heybour on cards produced for use of sticky back postal stamps. There are not official U.S. Postal Service stamps, but decorative stamps which illustrate 16 different Grand Rapids views, mostly buildings.