My personal and professional life collided recently. By an admittedly rough estimate, some five million cars have returned to campuses throughout the country in the past few weeks, and a couple of them were mine.

While their student users are in class, cars collectively occupy some 60 square miles of campus space, most of this being land allocated for parking. Back them up end to end (a common occurrence on many campuses these days) and these cars would stretch over halfway around the globe, or from Boston to Berkeley and back again—twice. Arrange them side by side (a common occurrence on the roads leading to campuses) and they would cover metropolitan Washington.