The locomotive fleet has a varied history. DRIR 417 (NW2) was originally SLSF (Frisco) 257. DRIR 1211 (SW1500) is ex-UPY (Union Pacific) 1211, exx-SP (Southern Pacific) 2646. Purchased from UP on April 22 2003. DRIR 1083 (SW1500), ex-UPY 1083, exx-SP 2480, which was also purchased from UP on April 22 2003. DRIR 996 (NW2) which is ex-BN (Burlington Northern Railroad) 419, exx-SLSF 259. DRIR's SW1, with no number, was ex-BN 88.
In June 2005, the Denver Rock Island Railroad, filed with the Surface Transportation Board a verified notice of exemption under 49 CFR 1150.41 to acquire from Union Pacific Railroad and operate rail lines commonly known as the Stock Yard Lead and the North Washington Industrial Track in Denver and Adams Counties, Colorado. The Stock Yard Lead consists of track extending from a point of connection with a UP main line north of East 58th Avenue in unincorporated Adams County to a point of connection with existing DRIR trackage at or near Race Court in the City of Denver, Denver County, a distance of 5,750 feet, or 1.09 miles.