What is the shelf life of a freshly baked donut? Two days, tops. But when it comes to an entirely different kind of donut—one that Stanford economist Nicholas Bloom described early in the pandemic when he measured the exodus of people from city centers to city suburbs—there appears to be no expiration date.... Since the pandemic, the country's 12 largest cities have cumulatively lost 8% of their downtown dwellers. Three-fifths of the households that left moved to nearby suburbs... What does this mean, then, for the country's biggest cities? Painful choices that will likely involve cutting spending, raising taxes and...