While cleaning the trunk, I removed the carpet and the cover over the spare tire. On the driver side directly behind the wheel there is an open access to an area where sand has collected. There is a vent along the side that opens up to allow access to the outside air.

Since I drive where roads are salted frequently, I'm wondering how much of that is salt. Fortunanetly it is dry in there (now).

Seems like it would be an area that would eventually rust although there is no sign of it now.