I just learned today that at least one part of the U.S. Government is working. The Internal Revenue Service!
I made no assumptions about the IRS being open or closed by Donald Trump's shutdown. I sent my quarterly estimated Federal Income Tax payment by the due date. Normally, the IRS takes a few weeks to cash my check. When I checked my bank balance this morning, I found that my check had been cashed by someone. I can only assume that it was the IRS; the image of the back of the check is hard to read.