Hi Paul, Here in the state of Pennsylvania all beekeepers must register the location, number of colonies and home address of keeper. There is a $10. fee for this and is to be done every other year. The money collected from these fees is to offset the expense of the bee inspection program. If you should be caught without registration you are warned the first time, after that, if you fail to obey they can fine you up to $1000. Of course there are those who do not register because they just don't know about the law (like me for example) I was not registered the first year because I just jumped into bee keeping without attending any classes, meetings or mentoring of any kind, and then there are those who ignore the law. I have one beekeeper friend who swears he will never register his single hive. Maybe there are others throughout the U.S. who can give you better insight into the accuracy to the number of bee keepers across our nation. Ron Harriger 100 Rhoades St. Cambridge Springs Pa. 16403