I bet you thought that trapping and killing beavers had ended long ago, but you would be wrong. Beaver fur is still used to make felt. It is primarily used to make Stetson hats (cowboy hats) and some Women's Hats. The fur makes the hats water repellent. With the prices of the hats in excess of $300 each it does not look like the killing of beavers for their fur will end soon.
So how many beavers have to die for one hat? It takes about 4 pounds of fur to make one hat so it would depend on the size of the beaver.
I did a brief search of the internet and could not find any place that bred and raised beavers for the fur trade so I can only assume that wild beavers were still being trapped.