This U.S. Geological Survey (USGS) data release provides whole rock major, minor, and trace element geochemical data, mineral chemistry, and monazite and xenotime geochronology for Proterozoic rocks in the Needle Mountains of southwestern Colorado and for Proterozoic rocks sampled from drill cores from Colorado, North Dakota, Nevada, Wyoming, Montana, and Nebraska. Samples from the Needle Mountains were collected in order to constrain the polyphase tectonic evolution of the area. Additionally, multi-scale compositional mapping, petrologic modeling and in-situ geochronology constrain the pressure-temperature-time paths from basement gneisses and quartzites. Drill core samples are part of a larger characterization of the age and geochemical character of basement terranes in the United States.