The mean of deep heat-flow measurements in the interior of the Colorado Plateau (temperature measurements to depths >750 m) is about 5 mWm-2 greater than the mean of shallow data. Although these data sets have remarkably similar means considering the experimental difficulties in measuring heat flow, the means never the less appear statistically different (59 mWm-2 vs 64 mWm-2). If various lithospheric heating models are used to explain the uplift of the Colorado Plateau, a 5 mWm-2 difference in surface heat flow will make the time of lithospheric heating very different. Deep heat-flow data in the Colorado Plateau typically lack the large spatial variability that shallow data show. The deeper data should therefore relate better to regional geothermal trends caused by mantle thermal conditions and by crustal radioactivity. The deep heat-flow data, where present, in the Colorado Plateau interior suggest a rather uniform heat flow and therefore rather constant mantle temperatures and crustal radioactivity. Continued concern with experimental data will be necessary to appreciate the uncertainties in the heat-flow data and the resulting thermal models.