title: List of rivers that have reversed direction
text: # List of rivers that have reversed direction
  
  A number of rivers are known to have reversed the direction of their flow, either permanently or temporarily, in response to geological activity, weather events, climate change, or direct human intervention.
  
  ## Permanent reversals
  
  ### Natural
  
  | River | Original outlet | Current outlet | Continent | Date of reversal | Cause of reversal | References |
  | - | - | - | - | - | - | - |
  | Amazon River | Pacific Ocean | Atlantic Ocean | South America | Cretaceous period | Formation of Andes Mountains | |
  | Wisconsin River | Great Lakes Basin | Mississippi River | North America | Pleistocene Epoch | Pre-Illinoian glaciers | |
  
  ### Artificial
  
  | River | Original outlet | Current outlet | Continent | Date of reversal | Cause of reversal | References |
  | - | - | - | - | - | - | - |
  | Chicago River | Lake Michigan | Mississippi River | North America | 1900 | Construction of Chicago Sanitary and Ship Canal | |
  
  ## Temporary reversals
  
  ### Daily
  
  All tidal sections of rivers reverse their flow with the tide about twice a day (or semidiurnally), by definition. The following are notable examples.
  
  | River | Outlet | Continent |
  | - | - | - |
  | Hudson River | Upper New York Bay | North America |
  | Saint John River (Reversing Falls) | Bay of Fundy | North America |
  | Salmon River | Bay of Fundy | North America |
  
  ### Annual
  
  | River | Outlet | Continent | Cause of reversal |
  | - | - | - | - |
  | Krupa River | Neretva River | Europe | High water levels of the Neretva River |
  | Petexbatún River | Pasión River | Central America | Winter rain flooding of the Pasión River |
  | Qiantang River | Hangzhou Bay | Asia | Tidal bore in Hangzhou Bay |
  | Tonlé Sap River | Mekong River | Asia | Monsoon flooding of the Mekong River |
  
  ### Intermittent
  
  Hurricane storm surges often cause temporary reversals of coastal rivers.
  
  | River | Outlet | Continent | Date of reversal | Cause of reversal |
  | - | - | - | - | - |
  | Chicago River | Mississippi River | North America | 2017 and others | Storm surge |
  | Mississippi River | Gulf of Mexico | North America | 1812 | Tectonic uplift caused by New Madrid earthquakes |
  | Mississippi River | Gulf of Mexico | North America | 2005 | Storm surge from Hurricane Katrina |
  | Mississippi River | Gulf of Mexico | North America | 2012 | Storm surge from Hurricane Isaac |
  | Mississippi River | Gulf of Mexico | North America | 2021 | Storm surge from Hurricane Ida |
  
  * ↑ These reversals represent a return to the Chicago River's original natural outlet in Lake Michigan.
  * ↑ Reversals of the Chicago River have been increasing in frequency in association with global warming, and may soon occur at least once each year.
  