The point here is not to cast blame on mayors or governors for the timing of what were difficult decisions for both public health and the economy, but rather, to alert cities and states where full social distancing measures are not in place that hesitation can come at a very high cost.

We also looked at state estimates and illustrate two that have only recently introduced statewide stay-at-home provisions (April 3 for Mississippi and Florida), and one that has yet to do so (Iowa, for which we selected April 14 for a possible stay-at-home order). The results for a one- or two-week earlier start on statewide policies are consistent and resemble those for the United States as a whole: Applying social distancing one week earlier is associated with a 60 percent reduction in the expected final death count.

The percentage reductions are, of course, estimates but this hardly blunts the take-home message.