On March 14, 1844, before Florida was a state, the territorial legislature created St. Lucia County from the southern part of Mosquito County, stretching from Cape Canaveral to near Orlando, and diagonally south to near Pompano Beach. In 1855, when the county’s name changed to Brevard, the boundaries also changed, and the area now known as Palm Beach County became part of Dade County. A new St. Lucie County was carved out of Brevard County in 1905. Click here for a series of maps showing the evolution of Palm Beach County at Palm Beach County History Online, brought to you by the Historical Society of Palm Beach County.
St. Lucie County in 1850 (map courtesy of the Exploring Florida Maps collection at the University of South Florida Center for Instructional Technology)