The
Aucilla River rises close to
Thomasville,
Georgia, USA, and passes through the
Big Bend region of
Florida, emptying into the
Gulf of Mexico at
Apalachee Bay. The river is long and has a
drainage basin of . The
Wacissa River is a tributary. In
Florida, the Aucilla River forms the eastern border of
Jefferson County, separating it from
Madison County on the northern part, and from
Taylor County to the south. The lower part of the river disappears underground and reappears several times, and is known as the
Aucilla River Sinks. The Aucilla River is a rich source of late
Pleistocene and early
Holocene animal bones and human
artifacts, and is the subject of the Aucilla River Prehistory Project, which includes the
Page-Ladson prehistory site. During the
first Spanish period in Florida the Aucilla River was the boundary between the
Apalachee people and the
Timucua-speaking Yustaga (or Uzachile) people.