Thanks for your comments! I was thinking about the mask signs while watching Jannis Androutsopoulos's presentations comparing first wave and second wave signs in Hamburg. I don't know if you've seen it yet; he found that first wave signs were business's signs, requested mask-wearing, and positioned addressees as customers, while many 2nd wave signs were (municipal or regional) gov't signs, used the imperative form, and positioned addressees as citizens. In the DC/US mask signs that we looked at, partly the issue is that mask-wearing in general was/is so politicized in the US, but watching Jannis's presentation, I also realized that it's an example of the downscaling of government functions to the local level. Certainly in DC, and my guess is also throughout the US, government masking and social distancing signs in public spaces are virtually non-existent. So I think what's happening is that this regulatory discourse is getting picked up by Business Improvement Districts and individual businesses -- and in taking up the discourse, they are take up the concomittant imperative form, and orient to people as both citizens and customers. Here's two examples from signs put up by the neighborhood Business Improvement District: It's also interesting to see how many presentations basically the same social distancing icon turned up in! I wonder if that comes from the WHO.