Union violence in the United States

Union violence in the United States is when a group of people who are part of a union use violence to get something they want. A union is a group of people who all have the same job and they join together to speak with their bosses as one group of people. Sometimes the bosses don't listen to the group and then the group gets angry and uses physical violence like punching and fighting to get their way. This is wrong and it's not a good way to get what you want.