From 2004 until 2006, increased volcanic activity at Mount St. Helens caused a surge in tourist traffic on SR 504, along with periodic shutdowns of the Johnston Ridge section. An evacuation of the area was ordered in early October 2004 due to seismic activity, indicating a possible buildup of magma, forcing 2,500 visitors to leave the Coldwater and Johnston centers for several days. The evacuation was later cancelled and other restrictions were relaxed after steam eruptions diffused pressure inside the volcano. A minor mudslide in March 2007 blocked a section of SR 504 near Kid Valley and was removed after a week-long cleanup by WSDOT crews.