Kind of - it closed the borders for Europeans traveling to the US, but did little to manage Americans returning from abroad. Given March is winter in the US (thus less tourism), I would imagine the majority of Europe -> US traffic at the time is Americans returning home, that's a rather weak closure.
I think you are diminishing the amount of traffic between Europe and US on any given day. Closing the borders to Europe may very well have saved us from catastrophe. Numbers exploded everywhere in March.
My point was that tourism to the US is probably not uniform throughout the year, and March is likely on the lower end of tourism. Hence the ratio of traffic being Americans returning home is higher.
