Residents of 860 homes in Washington state have been told to leave and at least 800 more houses are threatened by a wildfire that has raced across two square miles of forest, forced part of the area’s main road to close, and raised a plume of smoke that can be seen from Seattle. Worsening wildfire activity, driven by strong winds and high temperatures, has prompted the governor’s offices in both Washington and Oregon to declare a state of emergency, a move that enables state officials to call up the National Guard. In Washington, that declaration covers 30 eastern Washington counties.