In a way we have an experiment going on between California and New York since New York has so far declined to issue a shelter in place order. We'll really start to see if the curves diverge in another week, but new cases in New York already seem to be surging ahead of California.
Now Trump's tweet a few days ago makes sense...there was broad agreement across governors would enact shelter-in-place at a given benchmark, and Cuomo signaled otherwise...