A lot has been written about Baltimore recently, but the most insightful commentary often comes from people who are not directly addressing the news. Back in 2010, Antero Pietila wrote Not in My Neighborhood: How Bigotry Shaped a Great American City about Baltimore (h/t Tyler Cowen). The shaping was not subtle. Indeed, with a 1910 residential segregation ordinance passed by the City Council, Charm City literally invented the idea of legally enforcing neighborhood-level segregation:

Baltimore's innovation was the use of government legislation to achieve systematic, citywide race separation. "Nothing like it can be found in any statute book or ordinance record of this country," the New York Times wrote. "It is unique in legislation, Federal, State, or municipal—an ordinance so far-reaching in the logical sequence that must result from its enforcement that it may be said to mark a new era in social legislation." Baltimore thus became a national leader in residential segregation. Richmond, Norfolk, Roanoke, and Portsmouth in Virginia passed similar laws. And so did Winston-Salem, North Carolina; Greenville, South Carolina; Birmingham, Alabama; Atlanta, Georgia; Louisville, Kentucky, St. Louis, Missouri; Oklahoma City, Oklahoma; New Orleans, Louisiana; Indianapolis, Indiana; and Dallas, Texas. Like Baltimore, all those cities were trying to cope with a black influx. One letter of inquiry came all the way from the Philippines, where the U.S. occupation authorities wanted to know how Baltimore had done it.

There is much more in the book. But suffice it to say that once you corral a minority group into a confined geographical space, you don't follow that up by providing the space in question with first-rate parks, excellent schools, top-notch police service, useful transportation infrastructure, and high-impact neighborhood business development projects.

A growing body of research indicates that access to quality transportation is a key neighborhood-level determinant of upward mobility. But it's not some kind of cosmic coincidence that it's often the heavily African-American neighborhoods where this doesn't exist. The ghetto was a deliberate policy invention, and investing in a path out of it would have been completely contrary to the point of creating it.