Historic corridors are intact roadways and the surrounding environment that still convey their historic character from early in the 20th century. King County and other public agencies try to avoid impacts to these corridors during road improvement, maintenance or other public works projects. A few are officially designated landmark corridors and are subject to a higher degree of scrutiny during capital projects, but mostly the corridors support the development of heritage tourism in rural King County and raise awareness and pride among those who live or work along them.