Like others have posted most of Wyoming is less brushy than the south and areas like South Texas, where snake boots are warranted. I think the Black tail must be at the same level of aggressiveness as the prairie rattlers. We have stepped over these and they hardly even woke up. Sidwinders and Timber Rattlers are very active in comparison. When they come towards you I think it is curiosity rather than aggression.

A friend who works ranches in South Texas had his vision compromised by a stroke and he has had several strikes on his snake boots as a result. When you can't see them is when there is a problem.

"When you disarm the people, you commence to offend them and show that you distrust them either through cowardice or lack of confidence, and both of these opinions generate hatred." Niccolo Machiavelli