There were 100 fewer tests drilled in Colorado and western Nebraska in 1963 than in 1962, but with a slight increase in the over-all success ratio. Exploratory drilling in the Cambridge Arch area in Nebraska suffered a sharp decline but the success ratio increased from 4.2 percent in 1962 to 11.5 percent in 1963. Oil and gas production in Nebraska was 26,912,000 bbls. and 15,470 MMCFG; in Colorado 37,859,700 bbls and 159,650 MMCFG. There was a 51 percent decrease in geophysical activity in both areas.