America Had Other Great Lakes. Here's What's Left of Them.

In April 1997, downtown Grand Forks, North Dakota, was under water and on fire, and more than 50,000 people had left their homes. That flood started long before 1997. In the Ice Age, America had a lake bigger than all five Great Lakes put together, and it wasn't the only one. This countdown follows 20 of them, from a road that runs along an old beach above Duluth to a stadium that once sat under 950 feet of water in Missoula, the shoreline Salt Lake City is built on, a lake in Death Valley that moved two miles in the wind, and the waterfall that walked to Minneapolis. At number one: where the biggest lake went, and why two American cities still live on its floor. The 3D scenes are drawn from real elevation data with the water at its measured old level (one flat level; the real old shorelines tilt a little because the land has risen since the ice left). Some pictures stand in for moments no camera recorded. Chapters 0:00 Intro 0:55 20. The road on a beach 1:45 19. Where Ohio buried its dead 2:50 18. The Great Lakes' other exits 3:48 17. The lake that cut the Dells 4:53 16. The stadium under 950 feet of water 6:10 15. The line nobody can miss 7:26 14. The dam that failed in Idaho 8:09 13. Six rivers, one lake 9:06 12. The lake that cleaned Mark Twain's laundry 10:08 11. The lake that walked 11:32 10. 100 holes in a lake floor 12:23 9. Apparently boundless 13:23 8. The man who walked the shoreline 14:24 7. Bigger than all five 15:11 6. The trees remember the icebergs 16:00 5. The river too small for its valley 16:59 4. The waterfall that walked to Minneapolis 18:38 3. A door to the east 19:29 2. The lake comes back 20:40 1. The floor that still floods Sources - Lake Agassiz: North Dakota Geological Survey; Leverington and others (2002); Upham, The Glacial Lake Agassiz, USGS Monograph 25 (1895); Keating, Narrative of an Expedition to the Source of St. Peter's River (1824). - Red River floods: USGS; National Weather Service service assessment of the 1997 floods (1998); NPR and Prairie Public interviews; the diversion: EPA and the Fargo-Moorhead Area Diversion Authority. - Lake Missoula: USGS Information Leaflet 72-2; National Park Service, Ice Age Floods; Pardee, Journal of Geology (1910). - Lake Bonneville and Red Rock Pass: Utah Geological Survey; Idaho State University; Gilbert, Lake Bonneville, USGS Monograph 1 (1890). - Lake Lahontan: Russell, USGS Monograph 11 (1885); USGS (Benson and Mifflin; Reheis). Mono Lake: USGS; Mark Twain, Roughing It (1872). - Death Valley's 2024 lake: National Park Service. Lake Estancia: New Mexico Geological Society. - Lake Duluth: Green, Natural History and Geology Along the Superior Hiking Trail Through Duluth (2007); City of Duluth. Glacial Lake Wisconsin and the Dells: Wisconsin Geological and Natural History Survey. Lake Maumee and the beach ridges: Ohio DNR; Forsyth (1959). The Great Lakes: EPA, The Great Lakes Atlas. - River Warren and Saint Anthony Falls: National Park Service, Mississippi National River and Recreation Area; USGS; Minnesota Geological Survey; G. K. Warren (1874); MNopedia. Credits 3D scenes: elevation AWS Terrain Tiles (USGS 3DEP); imagery USGS The National Map; roads and the stadium outline © OpenStreetMap contributors (ODbL). Maps: NASA Blue Marble; USGS The National Map; Natural Earth. Archive film: Midwest Holiday (1952), Prelinger Archives. U.S. Coast Guard, FEMA, NOAA, NASA, USGS, National Park Service, National Archives and Library of Congress pictures are public domain. Photos via Wikimedia Commons, CC BY 2.0 / 3.0 / 4.0 and CC BY-SA 2.0 / 3.0 / 4.0, cropped: Sharon Mollerus, Joseph Gustafson, August Schwerdfeger, James Postema, Mbrickn, Quintin Soloviev, formulanone, Tony Webster, w_lemay, Daniel Mayer, Djembayz, Famartin, JOR Engineering, Steve Baskauf, Noahidsmith, Tammyjoanderson.taft, Tyler Vigen. Mark Twain's portrait is from 1867, a few years after his Mono Lake months. Stock footage licensed from Storyblocks.