The National Criminal Justice Reference Service (NCJRS) is a federally-funded resource that provides access to abstracts of journal articles relating to criminal justice, as well as reports and other resources from a variety of agencies under the Department of Justice (including the Bureau of Justice Statistics). The search is here. You can also email them to ask them a reference question (and search over questions that people have already asked).
The Sentencing Project is a nonprofit that advocates for changes in sentencing and alternatives to incarceration. Data from the Sentencing Project includes helpful maps and state-by-state data gathered from many of the sources listed in this section. The Sentencing Project also publishes reports and has a list of state contact organizations which may publish their own reports.
The Vera Institute of Justice is a nonprofit research and policy reform-oriented organization that consults on criminal justice issues, including mass incarceration, racial disparities, health in prisons, and alternatives to incarceration. Vera’s data visualization tool, Incarceration Trends, provides trend data on the number of people in jails and prisons for every county and state in the U.S. The data sources include BJS jail statistics as well as state level county prison reports, which are linked to.
The Sunlight Foundation is a nonprofit research foundation focused on transparency in federal, state, and local governments. Their Hall of Justice project collocates national, state, and local data on policing, incarceration, and crime. Don't click on the links to the right; they don't work (try the states or the search).
The Prison Policy Initiative is a nonprofit research organization that publishes reports and creates visualizations on trends in incarceration. The Prison Policy Initiative also curates a database of research reports from other organizations.
The Pew Charitable Trusts (a charitable foundation created in 1948 by the heirs to the Sunoco founder) publishes reports and briefs on prison reform and prison populations via the Public Safety Performance Project; see for example “One in 31: The Long Reach of American Corrections” and the issue brief “Use of Electronic Offender-Tracking Devices Expands Sharply.” The Pew Research Center, a subsidiary of the Charitable Trusts, also publishes reports on criminal justice.
Measures for Justice, a nonprofit funded by various business and governmental interests, collocates data on local criminal justice systems, by county. Data is currently available for 6 states.
The Citizens Police Data Project collects and visualizes information about police misconduct in Chicago.