Rich zinc ore discovered in this valley drew hundreds of people hoping for fortune. During the late 1800s and early 1900s, miners worked in 15 different mines that made up the Rush Mining District. In its heyday, more than 2,000 men, women, and children crowded the Rush area, living in tents, shacks, boarding houses, and hotels. Beneath the whir and clang of the mines and mills, communities slept, ate, toiled, and played, and their populations rose and fell with the price of zinc. With the onset of World War I in 1914, demand for zinc munitions products, including bronze and brass shell casings, tripled the value of zinc. As the war ended, the boom ended as well, and a zinc glut shut down Rush's operations as quickly as they had begun. Although mining continued here on a smaller scale for several more years, the Rush mining boom had run its course.