The West Virginia. Cyclopedia
Sunnyside was one of the early mining town established in the New River Gorge about a decade after the completion of the Chesapeake & Ohio Railway (C&O) in 1873. The company town was located between Mile Post 608 and 607 on the C&O mainline on the north side of New River, about 15 miles west of Thurmond.
The Sunnyside mine was first opened in 1885 by Strughan and Crump. Coal-mining operations at Sunnyside changed ownership several times during the life of the mine. West Virginia mining records  indicate the Sunnyside mine was operated by Reed, Lucas and Co. between 1884-1893; Thomas Coke Co. from 1894-1899; Sunnyside Coal & Coke during 1900; Victoria Coal & Coke in 1901; Isabel Coal & Coke during 1903-1905; and Sunbeury Coal & Coke Co. between 1906-1911.
The state mining inspectors' report, for the year ending June 30, 1901, reported that Sunnyside mine was working the Sewell seam, of 2'8" to 3'2" thickness. The mine opening was located 265 above the level of the railroad. An 700 foot long incline connected the mine with the tipple located along the railroad. The coal was hauled by miles from the interior of the mine and then run down the incline in wooden monitors, each having a capacity of 3 1/2 gross tons. It was noted that for several years the mine had experienced water drainage problems. The company was installing a new 2 1/2 H. P. gasoline pump in an attempt to solve its water problem.
A circa-1896 list of mines in the Third District of West Virginia listed the Thomas Coal Co. as operating the Sunny Side mine, a drift opening in the Sewell seam of 3-feet thickness. The company's post office address was Sunny Side. W. R. Bishop was mine superintendent and C. B. Adams was mine boos. The company employed 69 worked, and operated 18 coke ovens. The reported noted that the colliery presence of the coke ovens enabled the operation to ship "run of mine" coal the compared favorably with the lump coal from other mines.
The C&O track diagram of 1901 shows the Victoria Coal & Coke Co. at a station named Sunnyside, indicating a company store, tipple and coke ovens were in operation during that period. A 1906 C&O publication listed the Sunbuery Coal & Coke Company as operating one mine at Sunnyside, with 25 coke ovens in operation. Company officials included T.C. Buery, Pres., and John P. Vaughan, Gen. Mgr.
West Virginia mining records indicated that in 1910 Sunbeury Coal & Coke reported that none of its 15 coke ovens were in operation. The mining operation at Sunnyside apparently closed sometime around 1911. The USGS map of 1913, surveyed 1911, does not indicate a mines at Sunnyside.
Elmo is listed as a variant name of Sunnyside, however Elmo was actually a different mining town located about one mile east (upstream) of Sunnyside, as shown on the 1886 map at bottom, right.
 West Virginia Office of Miners' Health, Safety and Training, mine data tonnage reports
 Annual Report of the Dept. of Mines for the Year Ending June 30th, 1910 via Google Books