This is a geochemical data set from the reanalysis of 44 rock samples collected between 1966 and 1970, and 107 sediment samples collected in 1966 and 1967. These samples were collected by the U.S. Geological Survey for a study investigating the mineral resources of the Idaho Primitive Area (Cater et al., 1973). The samples are from the Lower Middle Fork of the Salmon River, including the tributaries of Big Creek, Camas Creek, Brush Creek, Wilson Creek, Waterfall Creek, Ship Island Creek, Reese Creek, Stoddard Creek, and Papoose Creek. The overall objective of this study is to characterize the regional impact of legacy mining for the Frank Church River of No Return Wilderness Area. Mary P. Rossillon (1981) explored the history of the Middle Fork of the Salmon River drainage basin, including mining. In 1864 placer gold was found on Loon Creek a tributary of the Middle Fork of the Salmon River and in 1869 considerable placer deposits were discovered at Yellowjacket Creek, a tributary of Camas Creek. In the early 1900s placer and lode deposits were being worked along Logan Creek, Smith Creeks, and especially the west fork of Monumental Creek, tributaries of Big Creek at the western edge of the Middle Fork area. Most placer claims filed in Middle Fork gravel bars were along a 5 mile stretch between Indian Creek and Lake Creek. In the early and mid -1900s lode mines were in the Middle Fork drainage area at the town of Yellowjacket, Loon Creek, Parker Mountain, Seafoam, Thunder Mountain, and the upper portion of Big Creek. Lode mines were generally located above the Middle Fork terraces, often in small tributaries a few miles upstream from the Middle Fork of the Salmon River. During the last decades of the 1900s the greatest activity in the Middle Fork basin was in and around the town of Yellowjacket (Rossillon, 1981). Stream sediment and rock samples collected for U.S. Geological Survey Idaho Primitive Area from the Middle Fork of the Salmon River area are summarized in Granitto and Lund (2020). The samples collected in 1966-1970 were analyzed using semiquantitative spectrographic methods for many different elements. Some samples were analyzed for cobalt while arsenic, copper, and heavy metals were analyzed for all sediments and some altered mineralized rocks. These methods did not produce total element data. Samples containing large amounts of rare-earth elements were analyzed by quantitative spectrographic. Samples were analyzed in several U.S. Geological Survey laboratories over a 4-year period using different analytical techniques. These techniques were modified and refined during this period (Cater et al., 1973). Consequently, not all the reported results summarized are directly comparable. A subset of the archived materials was reanalyzed using current and consistent techniques to allow sample comparability for all elements. Analytical techniques used for the reanalyzed samples reported here include a 60-element analysis following a Sodium Peroxide Fusion by either inductively coupled plasma – optical emission spectrometer (ICP-OES) or inductively coupled plasma – mass spectrometry (ICP-MS). Arsenic was also determined using hydride generation atomic absorption spectrometry (HGAAS) since the arsenic detection limit is 10 times lower for this technique. Thus, these new data for archived sediment and rocks form the Middle Fork of the Salmon River are internally consistent and directly comparable. References cited above: Cater, F.W., Pickney, D.M, Hamilton, W.B, Parker, R.L., Weldin, R.D., Close, T.J., and Zilka, N.T., 1973, Mineral Resources of the Idaho Primitive Area and Vicinity, Idaho: Geological Survey Bulletin 1304, p. 445. Granitto, M., and Lund, K., 2020, Geochemical Data Release for Idaho Primitive Area, including the contiguous Clear Creek-Upper Big Deer Creek Area, the Salmon River Breaks Primitive Area, the Sawtooth Primitive Area, and adjacent areas, central Idaho: U.S. Geological Survey data release, https://doi.org/10.5066/P9BT11RJ. Rossillon, M.P., 1981, An Overview of History in the Drainage Basin of the Middle Fork of the Salmon River, USDA Forest Service Intermountain Region Report No. 6, p. 94.