Vera Institute of Justice has released Incarceration Trends, a new interactive tool aimed at informing the public debate on mass incarceration by focusing on its front door and providing easily accessible information on jail populations in every U.S. county, including growth from 1970 to 2014, and racial and gender disparities in incarceration rates.

Vera also released a report, In Our Own Backyard: Confronting Growth and Disparities in American Jails, and an accompanying fact sheet. Project lead Chris Henrichson describes highlights of the tool and how to use it in this video.

Access to comprehensive and comparable data on incarceration at the county level is fundamental to reform. Now, justice system stakeholders and others can use this tool for reference and measurement by studying their own jurisdictions’ jails and how they compare with others over time.

A few highlights of the findings:

• Since 1970, there has been more than a four-fold increase in the number of people held in jail, from 157,000 to 690,000 per year, with jail populations growing faster than prison populations. Yet, while there is a growing recognition that jails are the front door to mass incarceration, until now there has been strikingly little data to guide jail reform efforts.

• Incarceration has grown the most outside of the largest counties. While the largest jails—such as those in NYC, LA, and Cook County—often draw the most attention and are the ones most often discussed by policymakers and the media, Vera found that these jails have not grown the most, nor are they among the ones with the highest incarceration rates. Surprisingly, mid-sized and small counties have largely driven growth. With four-fold growth rates in jail population from 1970 to 2014 overall, large counties grew by 2.8 times, while mid-sized counties more than quadrupled, and small counties experienced almost a seven-fold increase.

• African Americans make up nearly 40 percent of the jail population. African Americans have the highest incarceration rates, particularly in mid-sized and small counties.

• Female incarceration rates have skyrocketed, and are highest in the smallest counties. Since 1970, there has been more than a 14-fold increase in the number of women held in jail, from fewer than 8,000 women in 1970 to 110,000 women in 2014.

Explore your own county’s incarceration trends at trends.vera.org.