pretrial detention

An ACLU article "Criminal Conditions" discusses bail and local jails and states "More than 70% of those incarcerated - about half a million people - are pretrial detainees who have not been convicted of any crime, and many are only there because they could not afford bail.

I knew there was a problem, but such a high percentage surprised me. I wasn't sure if it included people in prison, nor did I know how many people are in jail versus prison. Nor was I even very clear on the difference between jail and prison.

So I looked it up.

Incarceration and Poverty in the United States (dated 2020/06/30)

The United States currently incarcerates 2.2 million people, nearly half of whom are non-violent drug offenders, accused people held pre-trial because they cannot afford their bail, and others who have been arrested for failure to pay debts or fines for minor infractions.
...
One-fourth of all those incarcerated in the United States (555,000 people) are being held pre-trial, primarily because they cannot afford to pay bail.
...
Nearly three-fourths of individuals held pre-trial have been accused of low-level drug or property crimes or other non-violent crimes.

Era of Mass Expansion: Why State Officials Should Fight Jail Growth (dated 2017 and quite informative, but most of the data shown is only through 2013)