@PFindlay Thank you very much for the reminder of using that particular reference source. I've had limited success with this source in the past, but this time, I think I hit pay dirt.
Using the Oregon vehicle registration records, I was able to identify license number 6016, issued in 1913 to the Estate of Jacob Kamm, for a Chalmers automobile, serial number 3022. This was the only year that this license number was associated with a Chalmers vehicle. The Chalmers with serial number 3022 remained with the Kamm family until 1916, when it disappears from the records.
It definitely makes sense that this Chalmers was associated with the Kamm family, since there were two other postcards of the Kamm family's Portland residence that came with this particular postcard. Based on my research, the woman at the steering wheel is most likely Caroline Augusta Kamm (1884-1952). She licensed the same car under her name until 1916, when it disappears from the records.