This compilation reports the results of 296 K-Ar analysis that were done during 1971-1991 on rock samples from throughout Arizona and, for a small number of samples, from bordering areas of adjacent states and from the Pinacate volcanic field of northwestern Sonora, Mexico. All of the reported analysis were done at the Laboratory ofIsotope Geochemistry at the Department of Geosciences, University of Arizona. Most of these dates have not been previously published. Those that have been published have not included analytical data. Some of these dates have not been released because, for various reasons, it seemed likely that they did not accurately represent rock age or cooling through the argon closure temperature. 57 pages.