As part of its mine subsidence research program, the Bureau of Mines and the American Electric Power Company cooperated on a study, conducted at the Price River Coal Company No. 3 Mine, directed toward developing the capability to estimate the surface subsidence resulting from longwall mining in a geologic, topographic, and mining environment common to coalfields in the Western United States. Subsidence was monitored at the No. 3 mine over two adjacent longwall panels. The subsidence study area was reuced when the two planned panels were reduced in length because of equipment failure and a mine fire. Subsidence was measured for 21 months. Subsidence continued for 6 months after mining had been completed. A maximum of 2.2 Ft of subsidence occurred over the two longwall panels mined at an overburden depth ranging from 800 to 1,500 ft.