Here's some good reporting from The Orlando Sentinel on Sanford, Florida's history:

Much of that tension stems from Sanford's long history as an agricultural community that attracted laborers, many of them black, to work in the fields, farms and railroads, historians say. They formed Seminole County's historic black communities of Georgetown, Goldsboro and Midway. 

Founded by laborers in the late 19th century, Goldsboro was once an active center of black life and became the second town in Florida incorporated by blacks. But in 1911, Sanford stripped Goldsboro of its charter and took it over. The streets, named after its black pioneers, were quickly renamed. 

"Ever since Goldsboro was taken over by Sanford, there has been tension," said Sanford Mayor Jeff Triplett.
Trymaine Lee has more on a history of police shootings. I don't want to house my man's story. Click through and read please. These tensions are old.