The NAACP used cartography to highlight lynchings in an attempt to garner support for the protection of their communities. This map uses a somewhat unusual but effective group of pattern fills to show statewide data.
A few years later this map appeared in a magazine called The Crisis showing lynchings between 1889 and 1921.
"Each dot on this map represents one of the 3,436 lynchings which took place in the United States between 1889 and 1921, a period of 32 years. The dots are all in the states where the lynchings occurred but naturally they could not be placed in the exact localities...but within the state boundaries." The way the dots are grouped within each state is strangely random as are the differing dot sizes.
These maps came from an article in Geography Realm
which highlights the contributions of black cartographers in creating maps for social justice. More info on this topic here