U.S. Census Office, Map Showing in Five Degrees of Density the Distribution of the Foreign Population (1874)

During the late 19th century, the United States experienced a significant increase in immigration, primarily from European countries. Many immigrants left their homelands due to job scarcity, crop failures, famine, political and religious persecution, and rising taxation. Drawn by the promise of economic opportunity, immigrants were especially attracted to the more industrialized northern states, where factory and manufacturing jobs were far more abundant than in the largely agrarian South. This settlement pattern is reflected in this choropleth map included in the 1870 Statistical Atlas of the United States, which was compiled under the direction of Francis A. Walker. Darker shading indicates higher population densities of immigrants, with the deepest concentrations appearing in major northern cities such as New York City, Chicago, and Detroit. These urban centers offered the employment opportunities that many immigrants sought upon arriving in the United States.