What is a primary underlying cause of the significant increase in the prison population in the United States over the past few decades?

One primary cause of the significant increase in the prison population in the United States over the past few decades is the implementation of tougher drug laws and "war on drugs" policies. These laws led to harsher penalties for drug offenses, resulting in many people being incarcerated for non-violent crimes. For example, someone caught with a small amount of marijuana could face long prison sentences, even if they were not harming anyone. This approach has disproportionately affected certain communities, contributing to a cycle of poverty and crime. As a result, the number of people in prison has surged, often for offenses that might have previously resulted in fines or treatment instead of incarceration.