Soft maple will dry rot twice as fast as cottonwood. Given the option of delivering soft maple for firewood, I always recommend cottonwood. In two years, soft maple rounds (such as silver maple) becomes so punky that they fall apart when you split them--even when stored off the ground.Right you are, Harry.
Cottonwood was even used for building houses - not just for flooring - around here in the 19th century. We have a string of old military outposts in north Texas that used a lot of cottonwood for their housing, hospitals, and morgues. The siding is even cottonwood! They were built ~1870 and several of these buildings are still standing. The hospital and BOQ at Ft. Richardson were built during the Indian Wars and were used off-and-on until the 1940s when they was set aside for use as a Texas State Park.
I wondered about the rot too. The park rangers told me that all the wood buildings were set on stone foundations, above the ground - so rot has never been a problem. My cottonwood firewood starts to get punky in a couple of years if it's stored on the ground in a damp area - but no problem if it's elevated.
xtm
I have never seen a cottonwod tree hollow out at the center as fast as a soft maple does. It also seems like the carpenter ants love soft maple and tend to avoid cottonwood. Not sure why. Perhaps the Forum could explain that one to me.