The early 20th century was an era of business expansion and progressive reform in the United States. The Progressivists, as they called themselves, worked to make American society a better and safer place in which to live. They tried to make big business more responsible through regulations of various kinds. They worked to clean up corrupt city governments, to improve working conditions in factories, and to better living conditions for those who lived in slum areas, a large number of whom were recent immigrants from Southern and Eastern Europe. Many progressives were also concerned with the environment and conservation of resources.