|Locale||Colorado, United States|
|Termini||Poncha Junction (until 1956)|
Salida (1956 - 1982)
|Connecting lines||UP Tennessee Pass line|
|Former connections||D&RGW Marshall Pass line|
|Owner||Denver and Rio Grande Western Railroad|
|Line length||15 mi (24 km)|
|Track gauge||4 ft 8 1⁄2 in (1,435 mm)|
|Old gauge||3 ft 0 in (914 mm)|
|Highest elevation||10,090 ft (3,080 m)|
The Monarch Branch was a branch line of the Denver & Rio Grande Western built in the 1880s to serve the Colorado Fuel & Iron limestone quarry at Monarch, Colorado. Originally part of the D&RGW's 3 ft 0 in (914 mm) narrow-gauge system, the 15 mile line connected with the rest of the narrow-gauge network at Poncha Junction, on the Marshall Pass line. The upper part of the Branch was on a 4.5% grade and included both an "S" curve and a double switchback to reach an elevation of over 10,000 ft (3,000 m). The line was converted to standard-gauge in 1956 after the narrow-gauge mainline from Salida to Gunnison was closed in the early 1950s. From that time forward, the line operated as a standard-gauge branch of the D&RGW until the early 1980s when Colorado Fuel & Iron closed its blast furnaces at Pueblo, Colorado. Operations on the Monarch Branch subsequently ceased and the rails were pulled up a short time later.
During the later narrow-gauge era, the line was worked with the D&RGW's fleet of K-36 and K-37 2-8-2 steam locomotives. Depending on the direction, trains would run either double headed or with a banker on the steep gradients. Once the switchbacks had been reached, each train was broken up and run in sections. Loaded trains then traveled to the D&RGW's yards at Salida, where the Stone was transferred to standard gauge gondola cars via a purpose built rotating 'barrel'.
Once the branch was converted to standard gauge, trains ran double-headed with D&RGW 4-axle EMD GP9s and in later days GP30s, GP35s and GP40s. During this period of operations, each train was broken up before the climb up the steep grades. 6-axle SD9s were tested on the branch but derailed due to the tight curves. Diesels assigned to the branch were given modified dynamic brakes to cope with the 4.5% grades.
- "DRGW.Net | Monarch Branch". www.drgw.net. Retrieved 2018-05-17.
- "The Monarch Branch of the D&RGW, edited by Russ Collman – Colorado Central Magazine". cozine.com. Retrieved 2018-05-17.
- "PAGE 99 - July 2010 - Carendt.com". Carendt.com. 2010-07-01. Retrieved 2018-05-17.
- "Rio Grande's Monarch branch out of Salida, CO". Trainorders.com Discussion. Retrieved 2018-05-17.