The prison population in the United States began to rise in 1972, and increased every year between 1972 and 2010, and by that time the number of prisoners was about 8 times what it was in 1972. In 2011, the national prison population dropped slightly for the first time in a generation. It has been on a slight decline since. This talk reviews the factors that fueled the almost 40-year growth in incarceration, and then assesses why prison populations are now showing evidence of slight decline. Whether this decline is a permanent change in the punitive landscape, or a temporary sift, is discussed. The talk concludes with a review of what it would take to see a much larger change in true number of people behind bars.