This is a very neat old suitcase. It is large and heavy - measures approx 24.5" x17"x7" and weighs 12.5 pounds.  I am unsure how to date it.  Oshkosh Trunk Company was around from the late 1800s though 1961.  Looks to be like black leather, and is a bit dusty / dirty and has a good amount of wear from age / use (see photos).  Includes one hanger - see inside photos.  It also does have a musty odor.