Inside its sprawling stores across America, Walmart employees began pulling thousands of guns and ammunition boxes from retail shelves this week in a pre-election precautionary move to guard against mass looting amid social unrest. Meanwhile, National Guard units in many of those states were gearing up to protect their cities and counties from threats—foreign and domestic—in a range of missions from cybersecurity to poll watching. At the local level, mayors and police chiefs were holding press conferences to reassure constituents about public safety by delivering detailed strategies on how authorities plan to deal with potential voter intimidation, the possibility of violence and other election-related concerns.