The Salt Mine Beneath Detroit

Six hundred feet below the streets of Detroit lies a salt mine stretching across 1,500 acres. Since 1910, workers have descended into those depths to extract the mineral that keeps Michigan's roads safe every winter. Most Detroit residents drive over it daily without knowing it exists. But every January, when black ice threatens to send cars spinning into guardrails, that hidden salt rises to the surface and does exactly what salt was made to do.…