Without Hoover Dam, the structure in front of you, the modern Las Vegas you just toured almost certainly would not exist. Construction began in 1931 and required a workforce of more than 5,000 men at any given time, drawn from across a Depression-devastated nation by the promise of wages in an era when wages were scarce. The Six Companies consortium that won the construction contract built Boulder City as a planned government community to house the workers and their families — a city built in the desert to build a dam to tame the Colorado River.
Those workers needed entertainment. Las Vegas, thirty miles to the northwest, was the nearest place to spend wages outside the restricted confines of Boulder City, where alcohol was prohibited and gambling was illegal. The dam construction workforce poured money into Las Vegas's saloons, brothels, and early gambling establishments for four years, establishing the economic pattern that would define the city for a century: attract people with a reason to be in the desert, then separate them from their money through entertainment.
The dam itself is a triumph of American engineering: 726 feet tall, 1,244 feet across, containing enough concrete to build a two-lane highway from New York to San Francisco. The hydroelectric generators powered the neon signs of Fremont Street, lit the searchlights of the Strip casinos, and made the city's air conditioning possible. Las Vegas runs on electricity. The electricity comes from here.