It's incredible to me that Washington, D.C., can keep adding new museums. I would have thought that between the Smithsonian museums and the historical sites, the city would have hit saturation point years and years ago. However, recent additions to D.C.'s museum roster include the National Museum of the American Indian (2004), the Newseum (2008), and the newest Smithsonian, the National Museum of African American History and Culture (2016). All of them appear to be wildly successful. By the…