Today, D.C. is marked by contrasts. Neighborhoods on the eastern periphery of the central city, and east of the Anacostia River tend to be disproportionately lower-income. Following World War II, many middle-income whites moved out of the city's central and eastern sections to newer, affordable suburban housing, with commuting eased by highway construction. The assassination of Martin Luther King Jr. in Memphis, Tennessee on April 4, 1968 sparked major riots in chiefly African American neighborhoods east of Rock Creek Park. Large sections of the central city remained blighted for decades. By contrast, areas west of the Park, including virtually the entire portion of the District between the Georgetown and Chevy Chase neighborhoods (the latter of which spills into neighboring Chevy Chase, Maryland), contain some of the nation's most affluent and notable neighborhoods. During the early 20th century, the U Street Corridor served as an important center for African American culture in DC. The Washington Metro opened in 1976. A rising economy and gentrification in the late 1990s and early 2000s led to revitalization of many downtown neighborhoods.