The "new western history" movement emerged among professional historians in the 1980s, a belated manifestation of the 1970s "new social history" movement. The new western historians recast the study of American frontier history by focusing on race, class, gender, and environment in the trans-Mississippi West. The movement is best known through the work of Patricia Nelson Limerick, Richard White, William Cronon, and Donald Worster. The philosophy and historiography of the new western historians is discussed thoroughly and supportively in Patricia Nelson Limerick, Clyde Milner II, and Charles E. Rankin, eds., Trails: Toward A New Western History. An overview of the New Western History is available in Clyde Milner, et al., The Oxford History of the American West. The movement has been thoroughly critiqued by historian Michael Allen.