In addition, racism, which had been viewed as a problem which primarily existed in the Southern states, burst onto the nation's consciousness following the Great Migration, the relocation of millions of African Americans from their roots in the rural Southern states to the industrial centers of the North and West between 1910 and 1970, particularly in cities such as Boston, St. Louis, Chicago, Detroit, New York City (Harlem), Cleveland, Los Angeles, Oakland, Seattle, Phoenix, and Denver. Within Chicago, for example, between 1910 and 1970, the percentage of African-Americans leapt from 2.0 percent to 32.7 percent. The demographic patterns of black migrants and external economic conditions are largely studied stimulants regarding the Great Migration. For example, migrating blacks (between 1910 and 1920) were more likely to be literate than blacks who remained in the South. Known economic push factors played a role in migration, such as the emergence of a split labor market and agricultural distress which resulted from the boll weevil destruction of the cotton economy.