Every ten years the Census Bureau works out where the United States would balance on a pin if everyone in it weighed the same. In 1790 the point was in Kent County, Maryland, a few miles outside Chestertown. In 2020 it was in Wright County, Missouri, out in the country; the nearest town is Hartville, population 594, which now has a survey mark to say so. In between it has walked about 886 miles, westward every decade and lately south as well. Nobody lives there because it is the centre, and nobody put it there. It sits where it sits because of everyone who lives somewhere else, which makes it the one spot on the map that every single person nudges a little, each time they pack up and move.