Why didn't the US Government put them on the terror watch list rather than on banned groups?

The KKK is a very bad group that does commit terrorist activities. Some people believe that the terror watch list is quite long and should only focus on the ISIS-type of groups because they commit more violence acts than the KKK. However, I believe that all groups should be on the terror watch list. There are several different lists for watching due to terror.

At one point, it is believed that the Ku Klux Klan was removed from the terror watch list, but they were placed on another list so that this one list was simply about Islamic terror. As long as the KKK is located on a list that takes it seriously to combat their behavior, it is okay with me.