What are the black flags at the US Capitol and why are there so many buses around the Congress

A number of requests have come in to film the black flags at the US Capitol building along with the seemingly endless parade of buses at the US Capitol. I went out yesterday to make some video of both of these things, but I also went through my archives over the last month and found some other videos that might be helpful. In short, it seems the black flags are POW, MIA flags that are now required to be flown at the Capitol, the White House, military cemeteries, and post offices due to a law signed by President Trump in 2019. The National POW, MIA Flag Act, Public Law 11667, was signed by President Trump on November 7, 2019 and should mean youll see this flag anytime you see the Capitol or White House on TV, or even when you visit your local post office. The second question was about the buses. Why are their tour buses when there are no tourists From what Ive seen, the National Guard has been using these unused tourist buses as a shuttle service. Ive gone back in my video files over the last