Hoover Dam was built from 1931 to 1936, with its construction completed and the dam formally finished in 1936. It was dedicated earlier, in 1935, by President Franklin D. Roosevelt. Key milestones:

• Construction began: March 1931
• First concrete poured: June 6, 1933
• Dam completed (last concrete placement): May 29, 1935
• Impounding of Lake Mead began: February 1, 1935
• Official dedication: September 30, 1935
• Powerplant completion and full completion of associated works: March 1, 1936

If you’d like, I can tailor this to a specific aspect (dates, milestones, or figures) or provide a concise timeline.