June 13, 2026
The Argo Mill
The Argo Mill began as a haulage tunnel between 1893 and 1910 in Idaho Springs, Colorado from which it ran 4.2 miles to Central City. The tunnel was constructed as a centralized and convenient means of ore removal for numerous mining operations in the surrounding area with the added benefit of draining water out of the mines. Prior to the tunnel, each individual mine had to extract, hoist and ship their ore uphill and out of town, ultimately to be used in the Denver Mint, which was a slow and tedious process. Furthermore, the mines wouldn’t receive payment until the ore made it to its destination and had its value assessed-which could take days. By connecting all the mines in the area with a tunnel underground, the Argo tunnel was able to eliminate all of the cost and effort of the logistics for the mines. Additionally, the Argo Tunnel was sold as a package to these mines along with electricity, compressed air, etc, which made it too good and convenient of a deal to pass up. In 1913, the Mill was constructed just outside of the tunnel so that all ore passing through the tunnel could be quickly and easily sorted onsite on the same day. This meant that the mines would now receive payment on the same day that the ore was hauled out. This was the best possible outcome for the mines. As a result, Argo became one of the largest such operations in the world. All of the mines in the area which made use of the Argo owe their success to the Argo Tunnel and Mill for the unparalleled convenience and cost savings this infrastructure provided.
On January 19, 1943, a catastrophe at the Argo Tunnel wiped out half of town and killed four employees. During WWII, mining operations were shut down. But a local entrepreneur was making preparations to restart operations as soon as it was allowed. He had employed several men to begin blasting out a new portion of tunnel but his calculations were off. The explosives used proved to be too much and the resultant blast breached the wall between the tunnel and a flooded section which was under extreme pressure. The water exploded out of the tunnel, killing the four men inside. One man, a brother to one of the men who just died, was closer to the portal of the tunnel, about 4 miles away from the blast. He was inside the tunnel when the explosion killed the lights and in the sudden darkness he heard the sound of water rushing towards him in the distance. He ran for the exit and not only did he survive, but he was able to sound the alarms. This gave the people of Idaho Springs just enough time to evacuate safely and, despite the fact that basically everything east of Argo in town was destroyed, no other fatalities occurred. The Argo Tunnel became one of the first EPA superfund sites and, according to the tour guides, the only such one the public can visit.
The Argo Mill sits just off HWY 70 less than an hour outside of Denver and is probably one of the most visible and recognizable tourist traps in Colorado. As such, it took many Colorado trips before we finally decided to take the time to stop and check it out. Overall, I’d say that it’s pretty cool and worth a stop. The mill seems mostly intact and it is interesting to see something like this and have things about the history and operations explained to you as you’re standing there which otherwise aren’t obvious. Although I found it to be a good way to spend 1-2 hours safely as a tourist I would say that it was fairly expensive for what it is, but that’s how it goes for tourist traps. I’d say the biggest disappointment is the fact that the accessible portion of tunnel is very small. Despite all the safety precautions and mandatory hard hats: You only get to walk about 100 feet into the tunnel before you reach the bulkhead and then you turn around and walk back out. And then there’s the gold panning.. But I won’t spoil that part. So, yeah.. As an adventurous person, the Argo tour is a bit underwhelming as most tours are. But it’s cool for what it is, you learn and see some interesting things and overall it’s worth doing once.
