Roll On, Columbia, Roll On near Cascades Rapids, in The Dalles, and on Memaloose Isle. The final three verses describe the construction of two Columbia River dams: Bonneville Dam and Grand Coulee Dam. Bonneville Dam, the first dam built on the Columbia, had locks built into it so ships could navigate past it, alleviating worries that a dam would prevent the shipment of goods and passengers along the length of the river. Guthrie's lyrics describe Grand Coulee Dam as "the mightiest thing ever built by a man"; when it was built it was the largest concrete dam in the world, and as of 2012 it
Grand Coulee Dam in the newspapers, stating exploratory drilling at the Grand Coulee site found no granite on which a dam's foundations could rest, only clay and fragmented rock. This was later disproved with Reclamation-ordered drilling. Ditchers hired General George W. Goethals, engineer of the Panama Canal, to prepare a report. Goethals visited the state and produced a report backing the ditchers. The Bureau of Reclamation was unimpressed by Goethals' report, believing it filled with errors. In , President Warren G. Harding visited Washington state and expressed support for irrigation work there, but died a month later. His successor, Calvin Coolidge, had little