Originally Posted by
Revracer
...wait a minute, Pacific Northwest is not at all a dry area as I spent a good amount of time in Seattle and a little in PDX...perhaps the rain washes them regularly?
Rust forms when water dries on iron (steel). So the number of rainfalls is what causes rust. In the PNW, it only rains once a year, for nine months. Then they get three months of no rain.