It was a mild spring morning in 2019 when a Postal Service city carrier drove up to a small, unassuming home in St. Louis, Missouri. As routine would have it, she walked up to the porch, picked up a Priority Mail package, and drove off. Except she wasn’t alone. As she tried to turn around on a one-way street, the sight of flashing lights caught her attention. Had she done something wrong? She certainly wasn’t speeding.