Around Chicago, Wednesday was one of the most lethal days of the pandemic, with more than 100 deaths. In the Boston area, where an alarming crisis of a month ago has given way to cautious optimism, businesses were reopening that day and new cases numbered in the dozens, no longer the hundreds. Around Rogers and Springdale in northwest Arkansas, which the virus had barely touched in the pandemic’s early weeks, poultry workers spent part of Wednesday planning a protest as outbreaks in at least two plants were driving a sudden surge in infection numbers. The dizzying volatility from city to city and state to state could continue indefinitely, with vastly different policy implications for individual places and no single, unified course in sight.