Electric trolley cars or trams were once the chief mode of public transportation in the United States.In 1922, auto manufacturer General Motors created a special unit to replace electric trolleys with cars, trucks, and buses.The decline of the tram system in North America could be attributed to many things-labor strikes, the Great Depression, regulations that were unfavorable to operators- but perhaps the primary cause was having a group of powerful men from rival sectors of the auto industry working  together to ensure its destruction.Fill it up, please.