If you were a miner back in the 1880s, how did you get really clean? You planned a trip to the closest hot springs. Hot spring trips have long been a traditional pastime in the BC-Washington-Oregon region, says Jeff Birkby, author of Touring Washington and Oregon Hot Springs, a history-rich guidebook to hot springs in the Pacific Northwest. Hot springs are formed when ground and rain water sinks below the Earth’s surface, then heats in volcanic pots deep below the surface. The mineral-infused water springs back out once it’s at a boiling point, then cools in pools. “Hot springs were social centers,” Birkby says of olden-days hot spring spots. The hotter…