It should be noted that there were no waffles on the road in IOWA or anywhere else, in 1947.   The 1947 Iowa license plate was a two-year issue, and waffle license plates were only issued in late 1948 with '48 tabs.  Though dated 1947, they were really never used WITHOUT the '48 tab.  Some of the tabs were also "waffle", some were not.

Iowa Note #2- Courtesy of George Sammeth, ALPCA #4013

In 1950, only non-passsenger type license plates were "waffle" plates in Iowa.   The license plate shown is for an Iowa trailer.

========================================================================

1948 Illinois "Prototype" Note, from Dan Nauth:

This 1948 Illinois Waffle Plate was found in a box of dollar plates at a flea market.

From information I was able to gather it was a prototype plate made by Hemp Manufacturing in Macomb, Illinois.  I spoke with Marly Hemp and he said this was made at his parents facility, as they were the supplier of Illinois plates for a number of years. 

Note the use of the numbers 1-5

They were experimenting with different styles, types and materials for the return to metal plates in 1949.  Thanks to the experts from the list and Marly Hemp for Identification and proof of authenticity.

=================================================================================