I agree with the c1948-1950 date for the Belvidere card. Consider these very similar additional cards ... all real photo, slanted upper-case writing for the labels, serial numbering:
1. Carthage, Indiana (Cook. Photo by Robert L. Carroll.)
2. LaGrange, Indiana (Used May 1948.)

3. Lebanon, Indiana (Cook. Used July 1947.)
4. Linton, Indiana

5. Portland, Indiana
6. Spencer, Indiana (Cook. Used June 1951. The license plates at the left end are too grainy to read a year, but the light lettering on a dark background may narrow it down.)

Interesting that the first one identifies the photographer as Robert L. Carroll. Was he a Carthage resident or did he do all of these?
The 3 labeled "Cook" have "All rights reserved - L. L. Cook, Co., Milwaukee" reading down the center of the reverse side. The remaining 3 have generic photo-paper backs.
I have additional cards which appear to be from the same photographer/publisher, but they do not contain autos, so are less useful.