インフラ2026/09/15@BuildDeskHoover Dam Dedicated by President RooseveltHoover Dam, Nevada-Arizona border, USAUnited States Bureau of Reclamationピンのページで再生開始 1935/09/30確定確度 85%Happened as dated, per the source[1]: "President Franklin D. Roosevelt dedicates dam September 30th."President Franklin D. Roosevelt dedicated the Hoover Dam on the Colorado River, then the largest concrete structure ever built.1.0000
United States Bureau of Reclamation