On April 25, 1860, the Rocky Mountain News reported, "The emigration is coming in at the rate of over one hundred men each day, and constantly increasing." Just a little over a month later, they reported that the emigrants were coming in at the rate of a thousand a day.

In June 1860, The Western Stage Company began running daily stagecoaches from Denver to Mountain City – the ride taking seven to eight hours. Only one year earlier, it had been a three or four day journey.  During the summer, the population around Gregory's Diggings began to stabilize. The 1860, the United States Census, listed Central City at 598, Mountain City 840 and Nevada City 879. About 5,000 people were in the immediate area and 34,000 in the mining region.

By August, 1860, the easy pickings were over and mining for gold became more difficult. As the depth of the mines increased, extracting gold from the ore became more complex. Due to the primitive technology, as little as 1/3 of the assayed amount of the ore was recovered. Other problems contributed to an economic slow-down in the area, including the Civil War and frequent Indian attacks on wagon trains crossing the Plains. The miners were becoming a rowdy bunch and in 1861, Central City recorded 217 fistfights, 97 revolver fights, 11 Bowie knife fights and 1 dogfight. Amazingly, no one was killed.

Central City became the county seat when Gilpin County was organized in 1861. The Territorial legislature granted a city charter to the City of Central in March 1864. This was 12 years before Colorado achieved statehood in 1876.

In 1865 Nathaniel P. Hill, a Professor at Brown University, began studying the problem of extracting gold from the sulfide ore. He developed a smelting process that rid the ore of most of its impurities, producing a concentrate of copper, gold or silver. The concentrate then had to be separated and refined.

In 1867, Hill began operating the Boston & Colorado Smelting Company in Black Hawk and mines began shipping ore to the smelter for processing. The concentrate of copper, gold and silver was then shipped to Swansea, Wales (over 7,000 miles away), where the metals were separated and refined.

As a result of this smelting and concentrating process, the district was "booming" again by early 1868. This "boom" resulted in extensive construction in Central City during the summer of 1868. The Daily Miner's Register of June 16, 1868 noted that: "No less than eleven brick store houses will be put up on Main street this summer. Hurrah for Central City." Two of those brick storehouses, built in 1868, survived the fire of 1874 and are still standing. They are the north half of the "Roworth Block" on Main street and the "Seavey Block" on Spring street.