RGS meaning in Regional ?

The Rio Grande Southern Railroad (reporting mark RGS, also referred to as "The Southern") was a 3 ft (914 mm) narrow-gauge railroad which ran in the southwestern region of the US state of Colorado, from the towns of Durango to Ridgway, routed via Lizard Head Pass. Built by Russian immigrant and Colorado toll road builder Otto Mears, the RGS operated from 1891 through 1951 and was built with the intent to transport immense amounts of silver mineral traffic that were being produced by the mining communities of Rico and Telluride. On both ends of the railroad, there were interchanges with The Denver and Rio Grande Railroad (reporting mark D&RG(W), later known as the Denver and Rio Grande Western), which would ship the traffic the RGS hauled elsewhere like the San Juan Smelter in Durango.

For the first few years of its life, the RGS would have fallen under the definition of a "Bonanza Railroad" which meant it was an instant success, quickly generating more than enough money for the investors and covering costs spent to build the railroad, but unfortunately their wealth wouldn't last long due to the Silver Panic of 1893, which would permanently cripple the railroad's finances.

The RGS closed down and was dismantled in 1952–3, but it is well known as one of the most rugged and iconic narrow-gauge mountain railroads in the history of Colorado.