Fort St. Louis or Fort Saint Louis or Fort Ste. Louis may mean one of several French forts of the late 17th century, two of which were founded by explorer La Salle

René-Robert Cavelier, Sieur de La Salle

René-Robert Cavelier, Sieur de La Salle, or Robert de LaSalle was a French explorer. He explored the Great Lakes region of the United States and Canada, the Mississippi River, and the Gulf of Mexico...

:

• Starved Rock, Illinois. Explorer Robert de La Salle founded Fort St. Louis atop the rock in 1682
• Fort Saint Louis (Illinois) redirects to Starved Rock
• French colonization of Texas. A French colony, Fort Saint Louis, existed near what is now Inez, Texas (USA). La Salle intended to found the colony at the mouth of the Mississippi River, but mislocated it far to the west.
• Fort Saint Louis (Texas) redirects to French colonization of Texas.
• Moose Factory, Ontario
  Moose Factory, Ontario
  Moose Factory is a community in the Cochrane District, Ontario, Canada. It is on Moose Factory Island, near the mouth of the Moose River, which is at the southern end of James Bay. It was the first English-speaking settlement in Ontario and the second Hudson's Bay Company post to be set up in North...
  
  . The French captured a fort there in 1686 and renamed it Fort St. Louis.
• Fort Ste. Louis (Nova Scotia)
• Fort Saint Louis (Martinique)
  Fort Saint Louis (Martinique)
  Fort Saint Louis is a fortress on a peninsula at Fort-de-France, Martinique. Today the Fort is both a naval base and an Historic Monument. There are daily tours of the fort, though the portion that is still a naval base is off-limits.-Naval Base:...
  
  is a 17th-century fortress in Fort-de-France, Martinique.

Built in the fall of 1682, La Salle created Fort Saint Louis des Illinois. After La Salle's five year monopoly ended La Barre wished to obtain Fort Saint Louis along with Fort Frontac for himself. By orders of the governor, traders and his officer were esscorted to Illinois. On August 11, 1683 Prudhomme obtained approximately one and three quarters of a mile of the north portage shore.