How is crime measured in the US?

Is crime in the US increasing or decreasing? It’s a question that the Department of Justice tries to answer using two primary sources: victim surveys and administrative data from law enforcement agencies.

The Bureau of Justice Statistics’ National Crime Victimization Survey captures information directly from victims, while the FBI’s Uniform Crime Reporting (UCR) Program collects data from law enforcement agencies. These data sources, which account for crimes that are reported to the police as well as those that aren’t, together provide a more comprehensive understanding of crime in the US.

In 2021, however, with only 64% of the US population covered by law enforcement agency participation, the FBI relied on crime estimates to compensate for the missing data.

Local and state agencies are not required by federal law to submit crime data to the FBI, making their participation voluntary.

FBI adopts a more detailed reporting system, law enforcement participation drops

The FBI has been collecting crime data from local law enforcement agencies through the Summary Reporting System (SRS) since 1929. SRS was replaced in 2021 by the National Incident-Based Reporting System (NIBRS), a more detailed reporting system.

In addition to removing the SRS Hierarchy Rule, which only recorded the most serious offense in a crime incident, NIBRS captures more information than SRS by allowing the data to count up to 10 offenses per incident and including more offense categories.

Although the FBI created NIBRS in the 1980s, law enforcement agencies were given until January 1, 2021, to switch to the new system, and some continued to submit data to the SRS until the deadline.

The results of the transition have been mixed. While NIBRS collects data for 42 more types of offenses and collects more details about victims and offenders than SRS, technological and cost-related challenges meant some law enforcement agencies missed the deadline for the transition.

Most agencies take a year to transition to NIBRS, while larger or more complex ones may need two years. This involves certification, implementing new software, personnel training, and acquiring funding. Washington, DC’s, government spent $50,493 to implement NIBRS in 2021, while the Maryland governor's office budgeted $2.5 million to ensure full NIBRS compliance for all local law enforcement agencies by the federal deadline.

Through the NIBRS Statewide Compliance Initiative, the Governor’s Office of Crime Prevention, Youth, and Victim Services has allocated approximately $2.5 million in Justice Department funding to support Maryland’s efforts to ensure 100% NIBRS compliance for all local law enforcement agencies by the federal deadline. The office anticipates making up to 50 awards. Priority will be given to agencies requesting technology enhancements.

Local law enforcement agency participation in SRS has historically covered greater than 90% of the US population, a number that dropped to 64% in 2021 with NIBRS. The FBI fell 16 percentage points short of its goal to have data from agencies serving more than 80% of the US population by 2021.

Notably, law enforcement agencies from New York City and Los Angeles, the two most populous cities in the US, did not submit data to NIBRS in 2021. The entire state of Florida also did not submit data to NIBRS that year.

Although many cities didn't provide data to the FBI in 2021, the FBI employs statistical methods, such as weighting, to fill in data gaps and produce crime figures that are representative of the country.

For a fuller picture of crime in the US, read about which states have the least and most crime. Get USAFacts data in your inbox by subscribing to our weekly newsletter.