When was Boulder Dam completed?
Boulder Dam, or Hoover Dam, was completed in 1936. It took place during the Great Depression. It is 726.4 feet tall.
The two names are referring to the same dam, so one is not older than the other. Hoover Dam was named for Herbert Hoover, the 31st US President. According to the Bureau of Land Management website, the name of the dam built as part of the Boulder Canyon project was always "Hoover Dam". That was stated by the Secretary of the Interior on Sept 30, 1930 when construction started and the name was made official…
As approved by Congress in the Boulder Canyon Project Act, $165,000,000 was authorized to complete the Boulder Canyon Project which includes the Imperial Dam, Hoover Dam and the American Canal. The Hoover Dam portion was $49,000,000. You can also visit this website for more info: http://historical.whatitcosts.com/facts-hoover-dam.htm