The "RS" simply stood for Road-Switcher and "1325" donated its horsepower rating, 1,325 (it was powered by EMD's late era, tried and proven prime mover the model 567D that carried 12 cylinders). The locomotive was 52 feet, 5 inches in length and used Flexicoil trucks. Interestingly, while Alco offered an entire line of "RS" road-switchers the RS1325 was the only of its type within Electro-Motive's catalog. Truth be told the locomotive was not unlike EMD's NW5, a design that harkened back to the mid-1940s. It also was sort of a half-switcher/road-switcher that sported a high, short hood which could also be equipped with a steam generator (overall the design was actually quite similar to Alco's successful RS1).
The NW5 ultimately sold only a few examples and at the time EMD expressed no interest in pursuing it further. For whatever reason railroads also found the RS1325 of little use. Again, perhaps the answer lay in the fact that the general public was not returning the rails as railroads had hoped in the 1950s. In the end, just one railroad found any interest in this unique EMD design, the Chicago & Illinois Midland located in central Illinois. The C&IM intended to use two, #30-31, in coal service (the road's primary source of traffic) as well as normal switching assignments. However, since steam generators would obviously not be needed the railroad ditched the higher short hood for a lower one; a sloped design like that found on the GP20 with a one-piece, full length front windshield for improved visibility.
During the next 36 years the two RS1325s remained in regular freight service on the C&IM wearing the road's common green livery with red trim. During 1996 the railroad was acquired by the Genesee & Wyoming (a large short line conglomerate) where it was renamed as the Illinois & Midland. The locomotive's then changed their green and red for G&W's corporate orange and black. Today, more than 40 years since the pair first entered service they can still be found pulling freights on the I&M despite their rare status. In an interesting twist of fate, the pair of RS1325s are the only original C&IM still in service on the I&M. With any luck, following the duo's retirement, whenever that time comes, they will be donated to a museum.
For more reading on Electro-Motive locomotives the book EMD Locomotives from author Brian Solomon highlights the history of EMD from its earliest beginnings in the 1920s to its phenomenal successes in the mid-20th century. It concludes by discussing the company's decline into second spot behind General Electric in the late 20th century and eventual sale by General Motors in 2005. The book features 176 pages of EMD history and is filled with excellent photography and illustrations. Another good title the author has written is entitled, GE And EMD Locomotives: The Illustrated History, which provides a general history of both company's locomotive lines over the years. As with all of Mr. Solomon's books expect a well-researched and written publication with crisp photography.