Some more on the history of these two towns.
MEXICO BEACH-- The area began to grow in the 1930s after the completion of US-98. In 1946, several business bought 1,850 acres along the beach for $65,000 with intentions of developing. The town incorporated in 1966.
PORT ST. JOE-- (Originally called St. Joseph) Sometimes referred to as Florida's Lost City. At one time the largest town in Florida, but essentially disappeared in the 1840s as a result of several factors, including a severe yellow fever epidemic and a particularly bad hurricane. Another one was it lost its economic competition with nearby Apalachicola. The population dropped from a high of 12,000 to 6,000 and by 1842, just 400 remained.
Interesting History. --RoadDog