The silver was difficult to exploit at first since the ore had to be taken to Leadville to be smelted. The route over the pass was long even in warm weather, and suited only for mule trains (even today, Highway 82 through it is closed during wintertime). Once the smelter at the Holden property was opened in the mid-1880s, mining profits and population grew rapidly, helped by the Sherman Silver Purchase Act's requirement that the federal government purchase the metal. Two railroads, the Colorado Midland and the Denver & Rio Grande Western, began building routes to the remote city, racing to be the first.