Final answer:
Boulder City was named after the original name of the dam project, the Boulder Canyon Project Act, which authorized the construction of what is now known as the Hoover Dam.
Step-by-step explanation:
The city where the workers lived was called Boulder City because it was named after the original name of the dam project, Boulder Canyon Project Act. Boulder City was constructed to house workers during the building of the Hoover Dam, which spanned the Colorado River and was completed in 1935. The name reflects the dam's initial designation before it was renamed in honor of President Hoover.