Reviewed and updated October 9, 2026 by the SearchSystems.net editorial team. The arrest counts are the ones each agency reported to the FBI, as the FBI held them on October 8, 2026. The jail figures are from the Vera Institute of Justice's Incarceration Trends data. Every office link was opened and checked against the office's own site on September 24, 2026.
Plymouth County, Iowa, has about 26,000 residents (2024 Census Bureau estimate). A person kept in custody after an arrest in Plymouth County is held at the county jail, run by the Plymouth County Sheriff's Office, and the jail's record of each person held is a public record. This guide says where to look for someone in custody, what the jail holds and who books people into it.
This guide covers the search, the jail, who books people, state prison and common questions.
Related guides: Plymouth County public records, Plymouth County arrest records, Plymouth County warrants, Plymouth County criminal records, Plymouth County court records, Iowa arrest records and Iowa inmate search.
Finding Someone in Custody in Plymouth County
The county jail, run by the Plymouth County Sheriff's Office, holds everyone kept in custody after an arrest in Plymouth County, from every agency.
SearchSystems opened and checked the jail page of the Plymouth County Sheriff's Office at plymouthcountysheriff.com/divisions/jail (page title: Jail | Plymouth County Sheriff's Office), phone 712-546-4419, which answered when SearchSystems opened it on September 24, 2026.
That page is the office's jail information page rather than a roster, so a search for a particular person goes through the office at 712-546-4419.
The Plymouth County Jail by the Numbers
On an average day in 2020 the jail held about 26 people, down from about 30 in 2019. Its rated capacity in 2019, the last year with a capacity figure, was 35 beds, and it ran at 86 percent of it that year. The figures are from the Vera Institute of Justice's Incarceration Trends data.
Plymouth County has about 26,000 residents (2024 Census Bureau estimate), so the jail holds about 10 people for every 10,000 residents.
Who Books People Into the Plymouth County Jail
The Plymouth County Sheriff's Office and the agency that reports for Le Mars make the arrests that end in a booking in Plymouth County.
The Sioux City Police Department is listed by the FBI across two counties including Plymouth County, so its arrests are not broken out for Plymouth County here.
The largest arrest counts reported to the FBI were Le Mars's 381 for 2025 and the Plymouth County Sheriff's Office's 225 for 2025.
Together, the two agencies in Plymouth County with all twelve months of 2025 on file reported 606 arrests to the FBI that year. Those kept in custody were booked into the county jail; a person cited and released at the scene was not.
The counts, agency by agency and year by year, are in Plymouth County arrest records.
From the Jail to State Prison
The jail holds people awaiting trial and people serving short sentences. A person sentenced to prison in Plymouth County serves the sentence in a facility of the Iowa Department of Corrections, whose inmate locator is at doc.iowa.gov/inmate-family-services.
Frequently Asked Questions
How do I find an inmate in Plymouth County?
Ask the Plymouth County Sheriff's Office at 712-546-4419; its jail page SearchSystems verified is at plymouthcountysheriff.com/divisions/jail.
How many people are in the Plymouth County jail?
About 26 on an average day in 2020, the latest year in the Vera Institute's jail data, against a rated capacity of 35 beds.
What is the phone number for the Plymouth County jail?
712-546-4419, the number on the page of the Plymouth County Sheriff's Office SearchSystems verified.
Where do people sentenced to prison in Plymouth County go?
To a facility of the Iowa Department of Corrections; its inmate locator is at doc.iowa.gov/inmate-family-services.
Is this the official Plymouth County website?
No. SearchSystems.net is an independent public records guide, online since 1997. It links to the official county, court and state offices described above and does not hold records, charge for them or take requests.