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A new, multicolor, geothermal gradient map of the continental United States has been produced as a joint publication of the National Geophysical Data Center (NGDC) and the Los Alamos National Laboratory (LANL). The map, which replaces the 1980 version published by LANL, presents a compilation of more than 1,700 wells that have been measured for temperature at depths greater than 50 m. Temperature/depth profiles are linear or are composed of linear segments reflecting changes in the thermal conductivity of the rocks. The data are displayed on two sheets, one for the east and one for the west, at a scale of 1:2,500,000. The location, depth, and gradient of each well is noted with a single, color-coded symbol. Each well also is numbered and keyed to a table showing latitude, longitude, well depth, gradient, heat flow (where available), thermal conductivity (where available), and a reference.