Between 1870 and 1920, around 20 million European immigrants arrived in the United States, primarily from Western and Northern Europe before 1890 and Southern and Eastern Europe after 1890. They were drawn by opportunities for work and escape from religious persecution or lack of jobs. Over 300,000 Chinese also arrived in the 1850s-1880s, attracted to work on the railroads and gold mines. By 1920, more than 200,000 Japanese lived on the West Coast. Most immigrants settled in cities where jobs and affordable housing were available. However, urban areas struggled with overcrowded and unsanitary tenement housing, inadequate sanitation and transportation, and other problems. Reformers worked to address these issues through settlement homes and social services.