Harley A. Harmon (1882–1947) was a pivotal figure in the early development of Las Vegas and Clark County, Nevada. Arriving in the region as a railroad engineer, he drove one of the first construction trains to Las Vegas in the early 1900s and quickly transitioned into public service. Harmon played a crucial role in advocating for the creation of Clark County in 1909, chairing the southern delegation at the Democratic State Convention that led to its establishment with Las Vegas as the county seat.

He served as the county's first County Clerk and, upon Las Vegas's incorporation in 1911, became its first City Clerk. After passing the bar in 1919, he was elected Clark County District Attorney, holding the position from 1921 to 1934, during which he vigorously prosecuted crimes associated with the Hoover Dam construction workforce, helping establish law and order in a rapidly growing area.

Harmon's broader contributions extended to securing vital resources for the region's future. As a member of the Colorado River Commission, he helped negotiate Nevada's water and power rights from the Colorado River and the Boulder (Hoover) Dam project, laying foundational infrastructure for growth.