In October 2015, the Million Dollar Hoods research team began using the California Public Records Act to request jail data from the Los Angeles Sheriff’s Department. We requested the name, arrest date, charge, release date, and home address of every person arrested by LASD. LASD twice denied the request before approving it in January 2016.

To fulfill the team’s PRA request, LASD provided the Million Dollar Hoods research team with html downloads of all LASD booking logs created between January 1, 2010 and December 31, 2015. The logs capture twenty-five categories of information, including the data requested by the research team, for every person arrested by a L.A. County Sheriff’s deputy and booked into the county jail system. During the six-year study period, arrests by LASD deputies resulted in 469,216 bookings into the L.A. County Jail system. For more on how the Million Dollar Hoods research team scraped, cleaned, geo-coded, and mapped the LASD data, see the team’s “Million Dollar Hoods Wiki.”

What is important to note about the LASD booking logs is that they provide just a peek at the total cost of incarceration in the L.A. County Jail system, which is operated by the Los Angeles County Sheriff’s Department. Here are just three of the reasons why the data is limited. First, LASD booking logs only include the period of incarceration between first arrest by a LASD deputy and initial release from the county jail. If a person bails out of jail but is later convicted and returned to jail to serve time, this additional time spent in jail is not recorded in the LASD booking logs.  Second, the L.A. County Jail system serves as the central jailing system within the L.A. area. The LAPD and other municipal police forces regularly book persons into the Los Angeles County jail system. Persons transferred into the LA County Jail system by these municipal police forces are not included in the LASD booking logs. Persons “re-aligned” or otherwise transferred to the L.A. County Jail system from a California State prison are also not included in the data. Third, ten percent of the entries in the LASD booking logs are missing home addresses or list “transient” in the home address category. None of these entries could be mapped. In other words, the LASD booking logs do not allow for every person incarcerated within the county jail system nor the total number of days they spent in jail to be tallied and mapped. In turn, the sums listed on the LASD layer of the Million Dollar Hood maps are just minimum estimates for the total cost of incarceration in the L.A. County Jail system. In many communities, the cost is actually much higher.

To calculate how much LASD spent per neighborhood, the research team needed to know the home address of every person booked into jail, the total number of days of they spent incarcerated, and the average daily cost of incarceration within the L.A. County Jail system. The booking logs capture home addresses and total days incarcerated for most persons booked into the county jail system by a sheriff’s deputy. But LASD budgets do not estimate the average daily cost of incarceration. To derive a method for estimating the daily cost of incarceration across the L.A. County Jail system, the research team examined the reports that the L.A. County Auditor-Controller produced to establish the reimbursement rates that other government agencies must pay to send individuals to L.A. County Jail facilities between 2010 and 2015. The Auditor-Controller splits the reimbursement cost into two parts. The first part is a one-time cost associated with “booking” an individual into jail. The second part is a daily “maintenance” cost. While the County Auditor-Controller calculations include variable costs (like staffing costs, travel and supplies), overhead costs, utilities costs, and accounting adjustments, our calculations only include variable costs. As a result, our estimates may be interpreted as conservative: they do not include costs associated with building facilities and keeping the lights on, administrating the jail system as a sub-unit of county government, providing health care, or interfacing with the law enforcement and court systems. Since reported costs vary considerably by year and by facility, we decided to use average costs across the entire inmate population for the period of the study. For both booking (B) and maintenance costs (M), we first took all relevant costs for each fiscal year prior to and overlapping with the calendar years included in the jail data (using actual costs where available and operational cost-adjustments in recent years). Then, we converted these costs to constant 2016 dollars and took the average, which yielded per-inmate estimates of $97.34 for the daily maintenance rate (M) and $269.65 for the one-time booking cost (B), averaged over the entire six years. Therefore, the formula we developed estimates that it would cost $366.99 to incarcerate one person for one day and $97.34 everyday thereafter, amounting to a  $35,798.75 commitment to hold one person for one year in the L.A. County Jail system.  For each neighborhood, the estimated maintenance rate (M) was multiplied by the total number of days in jail, and the estimated booking cost (B) was multiplied by the total number of bookings. The sum approximates the total cost of incarcerating the residents of an individual neighborhood.