The Invisible Line That Splits America in Two

Why do so few people live in the western half of the United States? It comes down to a line you can't see: the 100th meridian, where the rain drops below 20 inches a year. In 1878, John Wesley Powell, the one-armed Civil War veteran who led the first known boat trip through the Grand Canyon, warned Congress what that line meant. Congress didn't listen. Then came the Dust Bowl. And today, scientists say the line is moving east. Chapters 0:00 The invisible line at night 1:08 The 100th meridian and the 20-inch line 2:47 The one-armed explorer (1869) 4:44 Powell's warning to Congress (1878) 6:30 Rain follows the plow 8:19 The Dust Bowl 9:56 The line is moving 10:46 What Powell got right Exact numbers: West of 100° W: 48% of the land of the Lower 48, 24% of the people (2020); without CA, OR, WA: 37% of the land, 8.6% of the people. Annual rain: Kansas City 39.3 in, Wichita 34.3 in, Dodge City 22.0 in, Denver 14.5 in. Dust Bowl heartland (103–100° W, 35.5–38.5° N) in 1934: 11.4 in vs. an 18.2 in average. The 2018 study gives no fixed distance for the eastward shift. Footage (public domain): The Plow That Broke the Plains (Resettlement Administration, 1936, picture only), Rain on the Plains (USDA, 1938), A Heritage We Guard (USDA, 1940), The Living Land (Soil Conservation Service, 1941), Bureau of Reclamation films, NASA (Black Marble, Landsat), National Park Service (Grand Canyon). Photos and documents (public domain): Library of Congress (FSA/OWI photos by Arthur Rothstein and Dorothea Lange; Solomon D. Butcher; Carol M. Highsmith; railroad poster, 1872; WPA poster), National Archives (Homestead Act; Powell Survey photos by E. O. Beaman and John K. Hillers; Powell portraits), USGS (Hillers photographs; 1891 map; aquifer map by V. L. McGuire), National Park Service, NOAA (George E. Marsh Jr.), USDA Soil Conservation Service, FEMA, NASA, Smithsonian National Portrait Gallery (Charles Parker), engravings from Powell's 1875 report, scans via the Internet Archive. Maps, charts and the animated explainer sketches are our own (Natural Earth, NOAA, Census and USGS data); the 1869 route and the position of the line on the night image are simplified. Clips labeled "AI reconstruction" are AI-generated. Narration uses an AI voice; script written with AI assistance and checked against the sources above. #history #maps #america #dustbowl #geography