The R-1 locomotives were so large and heavy that the Chicago and North Western (C&NW) Railroad had to extensively rebuild their trackage, bridges, tunnels, turntables, and enginehouses to accommodate them.

They were able to travel all across the C&NW system by the 1940s, and they received varying modifications, including superheater installations and conversions to burn oil.

After the year 1900, railroad traffic in the United States was constantly growing, and existing locomotive rosters and rail infrastructures were becoming inadequate.

[2] By that time, the Chicago and North Western Railroad (C&NW) experimented with various firebox designs on steam locomotives to meet the demand for greater motive power.

[3] With the D class 4-4-2s earning recognition for their good performance, a freight locomotive design with the new boiler was being developed.

[4] The alterations added 2,000 pounds (907 kg) of weight for the locomotive, with the driving wheels bearing a large portion of it.

[12][13] While the Walschaerts application made the five locomotives several thousand pounds (kg) heavier than any Stephenson-powered R-1, their performance was deemed a success.

[17] In 1939, the railroad's program to upgrade their rail infrastructure for the R-1s had ended; by which time, the R-1's limited route availabilities were lifted, and they were permitted to travel anywhere on the C&NW system, when necessary.

[18] All forty Walschaerts-powered R-1s were built with steam-heating and air signal line equipment, so they were assigned to passenger service for most of their working spans.

[21] Also in 1915, the railroad made plans to rebuild some of the R-1s with larger cylindrical boilers, with the front section to be 72 inches (1,829 mm) in diameter.

[21] Despite the intervention from World War I and the United States Railroad Administration (USRA), the C&NW moved forward with the cylindrical boiler installations, with the process beginning in 1922.

[21] Beginning in 1911, the C&NW converted a number of their R-1 locomotives from coal-firing to oil-firing, to allow them to operate west of the Missouri River.

1329 and 175, were painted with white trim stripes for use in pulling occasional excursion fantrips throughout the 1950s, prior to their retirement.

[27][29] The SRI launched a fundraising campaign to rebuild and replace parts of the locomotive, with a large portion of the funding being administered by the Michigan Department of Transportation (MDOT).

[30] It was left in storage inside a roundhouse in Chadron, Nebraska, until June 1958, when it was acquired by William B. Heckman, the owner of the Black Hills Central Railroad.

[30] In Hill City, South Dakota Governor Joe Foss performed a Golden Spike ceremony, in commemoration of the locomotive's arrival.

444 was purchased by the Forney Transportation Museum, and the locomotive was towed to their location in Denver, Colorado, where it is currently being displayed.

1385 was subsequently used by the C&NW as a stationary boiler to thaw frozen iron ore, until November 1961, when the locomotive was purchased by the original members of the Mid-Continent Railway Museum (MCRM).

[19] The locomotive was later restored to operating condition, and it was used to pull the MCRM's tourist trains between North Freedom and Rattlesnake, Wisconsin.

[27] Between 1901 and 1910, the Chicago, St. Paul, Minneapolis and Omaha Railway (CMO) ordered a fleet of sixty-nine I-1 class 4-6-0 locomotives, and they were identical in design to the C&NW's R-1s.

[36][37] When the I-1s were first built, the CMO had to upgrade their rail infrastructure, in order to accommodate the locomotives' larger size and weight.

[36][38] The first thirty-five I-1s were initially fitted with clerestory-type roofs on their cabs—a standard practice that was exclusive to all CMO locomotives up to 1905.