Final answer:
The decrease in state inmates is a result of reforms in correctional policies, changes in societal attitudes towards incarceration, and an awareness of the social and economic impacts of mass incarceration.
Step-by-step explanation:
The recent decline in the number of state inmates has been attributed to major shifts in correctional policies. An initial expansion of the prison population from the 1970s through the 1990s was driven by various factors including mandatory minimum sentencing, a 'three strikes' law, and the 'war on drugs'. The country's incarceration rates have been further influenced by the cultural politics of the United States, where political candidates campaigned on being 'tough on crime', adding to this expansion.
In recent years, the realization of the social and economic costs of mass incarceration, along with an understanding of its limited effectiveness in resolving underlying social issues, has led to a reconsideration of these policies. The decriminalization of drug use, coupled with advocacy for prison reform and a reduced focus on incarceration for non-violent crimes, are all factors that have contributed to a reduction in inmate numbers. Additionally, the high costs of maintaining growing prison populations have forced states to seek alternatives to incarceration.
Furthermore, societal changes, such as awareness of the race and poverty aspect of incarceration and the impact of an aging prison population, have influenced the move towards revising prior policies. These adjustments in attitude and approach toward corrections and rehabilitation are reflected in the declining incarceration rates observed in recent years.