Among the millions of people incarcerated in the United States, a significant portion have long been thought to be parole violators, those who were returned to prison not for committing a crime but for failing to follow rules: missing an appointment with a parole officer, failing a urine test, or staying out past curfew.

But their actual number has been elusive, in part because they are held for relatively short stints, from a few months to a year, not long enough for record keepers to get a good count.

To help fill the statistical gap, The Marshall Project conducted a three-month survey of state corrections departments, finding more than 61,250 technical parole violators in 42 state prison systems as of early 2017. These are the inmates who are currently locked up for breaking a rule of parole, rather than parolees who have been convicted of a new crime; the number does not include those in county and local jails, where thousands more are likely held. (The eight remaining states — Alabama, Connecticut, Louisiana, North Carolina, Oklahoma, South Carolina, Tennessee, and Virginia — said either they did not keep current state-level data or it would be too costly to generate.)

The total, 61,250, seems small, given the 2.3 million people behind bars in this country. Imprisoning fewer technical violators would make only a dent in the effort to reduce mass incarceration. “But still,” said Marc Mauer, executive director of The Sentencing Project, “the numbers aren’t trivial.”

[For more of this story, written by Eli Hager, go to https://www.themarshallproject...iolations#.WwHlSdzm0]