Up until the time of Dr. Crow, pretty much all bourbon (or whatever it was called back then) was sweet mash ... not sour mash ... because Dr. Croe perfected the process.
For decades thereafter, there were a lot of sweet mash bourbons (I think some called it "mellow mash"). Primarily because of issues with product quality (it's easier to prevent bacterial contamination with sour mash ... and easier to preserve batch to batch consistancy) sour mash has dominated the category.
However, Sweet mash may be making a comeback ... primarily in the micro-distilled products (because it is easier to make sweet mash ... and sterilization has become easier as well). I am aware of some producers ... with product not yet on the market ... that will be introducing sweet mash products in the near future ... probably much better than the WR sweet mash was ...
Finally, the re-kindling of the George Washington Distillery at Mount Vernon involves only sweet mash rye ... for historical accuracy... and it will be pretty good ... whenever it finally hits the market.
It is unfortunate that many people think that the primary difference between TN whiskey and Bourbon is the sour mash process ... when it is not.... it is just that some brands toot the sour mash horn very loudly, while others do not.
Dave are these brands going to label their products as sweet mash or do you know?
[Liberty Valance lays shot in the street]
(Dr) "Quick whiskey!"
[ Dr drinks from whiskey bottle, kicks over Liberty Valance]
(Dr) "He's Dead"