Rocky Mountain Steel Long Rail Mill, Pueblo

The Pueblo long rail mill delivered its first 328-foot rail to Union Pacific in July 2026, five years after groundbreaking and about three years behind the original plan. Rocky Mountain Steel Mills built it inside a steelworks that has rolled rail since 1882.

Rails that long need 80 percent fewer welds than standard 80-foot sticks, according to Union Pacific. Fewer welds means fewer weak points in the track.

Project Scope

The mill stands on the former Colorado Fuel and Iron plant on Pueblo’s south side. EVRAZ North America broke ground in July 2021 on what it then called a $500 million project, with construction wrapping in late 2022 and rolling to start in 2023. Colorado Public Radio reported in early 2022 that the main building covers more than 15 acres.

Danieli supplied the universal rail mill: a breakdown mill, a tandem reversing mill, a cooling bed, and horizontal and vertical straighteners. The Italian plantmaker rates the line at 650,000 short tons a year of rail up to 100 meters long and 88 kilograms per meter, with hardness to 425 BHN. Hot commissioning began in December 2025.

Power comes from next door. Lightsource bp owns the 300-megawatt Bighorn Solar project on 1,800 acres of mill property, and McCarthy Building Companies finished it as EPC contractor in March 2022. Union Pacific’s announcement says its 750,000 panels cover up to 95 percent of the mill’s electricity.

A lot changed between groundbreaking and first rail. EVRAZ switched general contractors at the start of 2023, Steel Market Update reported at the time. The business changed hands in 2025 and now operates under parent company Orion Steel. Union Pacific signed a seven-year supply contract in April 2026.

Why It Matters

Start with the cost. The 2021 figure was $500 million. Union Pacific and Orion now describe a $1.2 billion investment in the new facility. Neither has published a breakdown, so it isn’t clear how much of the gap is escalation and delay and how much is a wider definition of the project. Treat the two numbers as bookends, not as a measured overrun.

The schedule slip is easier to read. A late-2022 construction finish became a mid-2026 first delivery.

What the owner got for the wait is a mill with few peers. Progressive Railroading calls it the only remaining dedicated rail production facility in the United States. The railroad that bought Pueblo’s first rail in 1882 has committed to seven more years of it.

There’s a construction lesson in the sequence, too. The solar farm, a simple and repetitive build, was finished in March 2022. The rolling mill, a one-off process plant threaded into an operating steelworks, took four more years.

Six hundred fifty thousand tons a year is the nameplate. The ramp will show how much of it the railroads take.

Project Team & Details