The FBI’s Uniform Crime Reporting (UCR) Program has transitioned from its legacy data collection system (a 1960 mainframe database) to a more modern reporting platform known as the Uniform Crime Reporting-Tech Refresh (UCR-TR). Beginning with the Preliminary Semiannual Uniform Crime Report, January to June 2018, published UCR data now comes from the UCR-TR, and not the legacy system.

The change in the computing platform may result in differences in UCR data from previous years, and program participants should use caution when analyzing data. Users should not assume that increases or decreases in published information are due to increases or decreases in crime—the difference may be because of technical and procedural differences between the UCR-TR and the legacy system.

Some differences between the UCR-TR and the legacy system are available in section 2 (beginning on page 6) of the November 2018 UCR Program Quarterly.