US Forest Service Wood Handbook. Black Locust is at the top of every list of all major strength categories for wood indigenous to the US per the USDA. | From the Wood Handbook, the USDA identifies Black Locust and Sassafras as “exceptionally high decay resistance”, the highest rating in the USA. | Oregon State Rot Resistance study of Fence Posts using more than 30 species over decades. Black Locust achieved top results for minimal decay. | Black Locust is the only known wood indigenous to the US that has tested to a Class A rating. | National Hardwood Lumber Association Rules for the Measurement and Inspection of Hardwood |