The U.S. built a staggering number of prisons in the 90s and 00s.

A new prison every 10 days for 15 years. That number sounds impossible. But a Congressional report entitled Economic Impacts of Prison Growth confirms the data. The report states, “The number of state and federal adult correction facilities rose from 1,277 in 1990 to 1,821 in 2005, a 43% increase.”

That means that during that 15-year span, 544 new correctional facilities were built. There are 5475 days in 15 years. If you divide the number of days by the number of facilities built, you end up with almost exactly a facility built every 10 days.

So why were so many prisons built during this time period? The short answer is to house an exponentially growing number of incarcerated people. In 1990, there were 771,243 people in state and federal prisons. By 2005, that number had climbed to 1,446,269. Those figures do not include the number of incarcerated people in jails at that time.
https://interrogatingjustice.org/ending-mass-incarceration/prison-every-10-days/