A recent NRA-ILA report explains how the Crime Prevention Research Center found that
"one factor contributing to the ostensible dip in violent crime is that almost 40% of local law enforcement agencies are no longer transmitting their information to the national Federal Bureau of Investigation (FBI) database."
Here's more from the NRA-ILA report:
In "2021, 37% of police departments stopped reporting crime data to the FBI (including large departments for Chicago, Los Angeles, and New York)," and for other jurisdictions, like Baltimore and Nashville, crimes are being underreported or undercounted. This leaves a large gap; by 2021, the real crime data collected by the FBI represented only 63% of police departments overseeing just 65% of the population. When compared to pre-2021 data, the result is a questionable "decline" in crime.
More from the Washington Examiner:
Bad data from the FBI mislead about crime - Washington Examiner