18- Mink Fire enters Yellowstone Park. A firewood cutter on the Targhee National Forest starts the North Fork Fire, the largest fire in the Fires of '88. This fire eventually threatened the West Yellowstone, Old Faithful, Madison Junction, Canyon Village, Tower Junction, and Mammoth Hot Springs developed areas. 23- Grant Village is evacuated. The Clover and Mist Fires merge to become the Clover-Mist Fire.
Major fires make large advances.
24- Shoshone Fire advances on Grant Village. Over 500 firefighters try to stop its momentum. Shoshone Fire crosses firelines and highway to directly threaten Grant Village. 27- Secretary of the Interior Donald Hodel arrives in Yellowstone for a first hand look at the fires. Under threat of a lawsuit from the Church Universal and Triumphant, bulldozers are deployed to the north boundary of the park to stop the Fan Fire from leaving the park.