The above answers cover this pretty well, but I feel compelled to post anyway, because if anyone knows the answer to this question it should be me – I’m a hubcap dealer
You are absolutely right, jimmmy, in postulating that more holes form after big snowfalls. Water is instrumental in the formation of potholes. It gets under the roadway and the expansion and contraction of the water during freeze-thaw cycles cracks the asphalt and pushes it out, forming a pothole. Deep snow does a great job of this, because it melts a little, freezes again, melts some more, etc.
This recent snowstorm seems to be doing the trick…a lot of it melted during the past few days, and now all that water is re-freezing as I type (the temp is dropping into the 20s tonight). I am practically jumping up and down with glee thinking about all the caps I will be finding on the roads this spring. I’m sure all you commuters are having a somewhat different reaction