There are mixed opinions of the value of the Cottonwood tree, In the opinion of James A Brauer, a blacksmith, knife maker, cabinet and furniture maker and accomplished wood carver, the Cottonwood is closer to a weed than a tree.  In the spring its seed pods clog up air conditioning coils, and gutters, and its wood structure because it is relatively fast growing especially near waterways is open grained and can contain soft spots that won’t hold fine detail making it unsuitable for carving.  Even as firewood it is unsuitable as it gives off a unpleasant odor while burning  
Conversely its bark is a wonderful source of carving material as its grain is quite fine and easy to carve.  Cottonwoods that grew in areas where water is less plentiful will still have a less favorable grain structure for carving while the bark will be more fine-grained than its cousins that grew near a more plentiful water source.  
Of the eleven species found in North America (there are 25 world-wide) only two have commercial importance.  They are the Eastern Cottonwood found from the Midwest to the Atlantic, and the Black Cottonwood found in the valleys of the Pacific Northwest.

To the Indigenous populations the catkins (the pendulous flowering growths) were a food source in the spring and they also learned that the inner bark had medicinal properties.  They also used the twigs and small branches to weave baskets.  

To the Pioneer homesteaders Cottonwoods, because they were fast growing, were ideal for windbreaks.  As well, in the winter the inner bark was often used to supplement livestock feed.  Because it is easily worked with hand tools it was a popular source of wood for rough furniture but was shunned by cabinet makers because it cannot be machined to a fine finish.