Dyer was distressed by such mob violence, with its disregard for the courts and the rule of law. His district in St. Louis had mostly African-American residents and he wanted to protect his constituents and other citizens. Many black people from his district had migrated to St. Louis from the South, in the exodus known as the Great Migration. They settled in St. Louis along with immigrants from southern and eastern Europe where industrialization had led to a strong economy and an increase in jobs. Dyer also knew of the continuing high rate of lynchings, mostly of blacks by whites in the South. Working with W. E. B. Du Bois and Walter White of the National Association for the Advancement of Colored People (NAACP), who had been working on a national anti-lynching campaign, Dyer helped develop and agreed to sponsor anti-lynching legislation.