New Orleans' economic and population zenith in relation to other American cities occurred in the antebellum period. It was the nation's fifth-largest city in 1860 (after New York, Philadelphia, Boston and Baltimore) and was significantly larger than all other southern cities. From the mid-19th century onward rapid economic growth shifted to other areas, while New Orleans' relative importance steadily declined. The growth of railways and highways decreased river traffic, diverting goods to other transportation corridors and markets. Thousands of the most ambitious people of color left the state in the Great Migration around World War II and after, many for West Coast destinations. From the late 1800s, most censuses recorded New Orleans slipping down the ranks in the list of largest American cities (New Orleans' population still continued to increase throughout the period, but at a slower rate than before the Civil War).