The climate in this area is characterized by hot, humid summers and generally mild winters.

A long time has passed since St. Marks last had appreciable importance, but this place on Apalachee Bay in Florida's Big Bend is a very old and historic Gulf port.

Fortifications built here by the Spanish in the 17th century, and rebuilt several times, provided the venue for force of arms repeatedly up through the American Civil War.

In the best-known incident, Andrew Jackson, in his incursion into Spanish Florida in 1818, executed British nationals Robert Chrystie Ambrister and Alexander George Arbuthnot at the old fort, as well as the Muscogee ("Creek") religious leader called Francis the Prophet.

San Marcos de Apalache Historic State Park interprets the site of the old fort.

Various articles in publications like Florida Historical Quarterly relate how the fort site later held a government "naval" hospital to meet yellow fever emergencies in the merchant marine.

[citation needed] The lighthouse stands, after a couple of reconstructions, at the mouth of the river six miles from town and accessible by road.

Ellen Call Long, on her way to Tallahassee, described the port about 1830 as "a quaint little village, amphibious-like, consisting of a few dwelling houses, stores, etc., mostly built on stilts or piles, as if ready to launch when wind or tide prevailed.

"[6]A railroad often cited as Florida's first[7] connected the port of St. Marks with the territorial capital, Tallahassee, some 20 miles inland.

The line, the Tallahassee Railroad, was constructed about 1836, and until the Civil War it served in the export of Middle Florida's cotton through St. Marks.