The Greenwood Massacre

The 1921 Greenwood Massacre in Tulsa is one of the most horrifying incidents in US race relations. This map via Tulsa World details the significant events that took place there.

You can click above for a more readable version. Here is a detail to get a feel.

There is a locator map in the corner but it shows the city pre-expressways and if you don't know the city very well it is hard to see where this is. Here is the Google Maps view. It looks like much of the neighborhood has been sacrificed for highways, a stadium and a university, a common fate for many African-American neighborhoods.