"Although jails are the “front door” to mass incarceration, there is not enough data for justice system stakeholders and others to understand how their jail is being used and how it compares with others. To address this issue, Vera researchers developed a data tool that includes the jail population and jail incarceration rate for every U.S. county that uses a local jail … The data revealed that, since 1970, the number of people held in jail has increased from 157,000 to 690,000 in 2014—a more than four-fold increase nationwide, with growth rates highest in the smallest counties. This data also reveals wide variation in incarceration rates and racial disparities among jurisdictions of similar size and thus underlines an essential point: The number of people in jail is largely the result of choices made by policymakers and others in the justice system. The Incarceration Trends tool provides any jurisdiction with the appetite for change the opportunity to better understand its history of jail use and measure its progress toward decarceration" (website). This website provides access to the Incarceration Trend tool for jails, summary, full report, a video tour of the tool with Chris Henrichson, and data and methods. Sections comprising the full report include: introduction; the expanding footprint of local incarceration—a snapshot of the findings—decades of growth, and growth's disparate impacts; understanding growth and disparities; using the Incarnation Trends tool; and conclusion. The Incarceration Trends tool is interactive and illustrates data per 100,000 county residents for: jail incarceration rate change (1970 to 2014); the 2014 jail incarceration rate; Black/African American jail incarceration rate; female jail incarceration rate; jail and prison incarceration rate for California and New York; what is trending in your county—exploring your counties jail data. One interesting finding is that the largest increase in the number of incarcerated individuals is occurring in mid-sized and small counties. Since 1970, local jail populations in mid-sized counties have grown 4.1 percent, small counties 6.9%, and large counties by 2.8%.