Alameda County, California (where I land several other million people live) has announced a "shelter in place" order effective midnight tonight. Here's a link to the order, and some thoughts on it in a thread. acphd.org/media/559658/h… 
The basic idea: STAY AT HOME! You can only leave your home, or keep an out-of-the-home business running, in a few specific situations. It applies for the next three weeks.
Here's some of the key language. Really, stay at home. Don't get together with people outside your home (no playdates for kids, parents). No trips unless it's for a specific allowed purpose. Really REALLY stay at home, with the other people who live with you. STAY HOME.
You can leave your home only to do certain specific things: seek medical care, getting food, getting supplies needed to work from home, caring for others, and a limited exception for "outdoor activity" (more on that below).
Also, you can leave your home to do one of the named essential jobs. The basic idea: Services needed to keep this system running and care for others are allowed. If your job isn't part of that, you can't leave home to do it.
People are also allowed to leave their home to keep businesses afloat -- so-called "minimum basic operations." You can go in to process payroll, for example, and the IT guy can go in to keep people online.
Also, people can go outdoors to go for a walk, run, or hike, as long as you follow the "social distancing" rules -- stay 6 feet away from others, wash your hands a lot, sneeze into your sleeve, etc. As I read the order, you're also allowed to drive to where you do this.
Finally, it's all enforceable criminally, but only as misdemeanors. I assume they really want voluntary compliance, but this lets them enforce rules if needed with cops breaking up parties, ordering people to go home, etc., although they don't want to bring actual prosecutions.
This is is extremely serious stuff, obviously. A week ago, it would have been unimaginable. But watching the world news, and seeing what is happening both locally and elsewhere, it seems not unreasonable, at least at this particular moment. Fingers crossed it will work. /end
