The Green Ridge Railroad was a 3 foot gauge line in the eastern part of Allegany County, running roughly north-south. The engines were built in Mt. Savage, Md., under contract to T. H. Paul of Frostburg, for sale to Mertens. Two engines were rostered.

Green Ridge Number 1 is featured in an illustration of the Mt. Savage catalog, as the model for the 0-6-0 units. GRRR Number 2 is an 0-4-0 unit. The rail line was eight miles to the east of Cumberland, in the vicinity of Town Hill, and Fifteen Mile Creek. It belonged to the Mertens family, and supplied lumber to a sawmill at Oldtown, for use by the Merten's boatyards in Cumberland to construct canal boats. The railroad operated from 1889 to 1897. It interchanged with the B&O railroad near PawPaw, WV, after crossing the Potomac on a trestle.

The Green Ridge Railroad was built by the Mertens Company in 1889, some 8 miles east of Cumberland. It initially consisted of 16 miles of 3 foot gauge track. The railroad made connection with the B&O Railroad at Okonoko, WV and with the C&O Canal at Darkey's Lock (lock 67). By 1896, the line had grown to 26 miles of track, and had a passenger car. The rail line was closed in 1897.