Final answer:
The U.S. uses two official measures of crime: the Uniform Crime Reports and the National Crime Victimization Survey, but a new system, the National Incident-Based Reporting System, will provide more detailed data from 2021.
Step-by-step explanation:
The United States utilizes two official measures of crime, which are the Uniform Crime Reports (UCR) and the National Crime Victimization Survey (NCVS).
The UCR is compiled by the FBI from data provided by around 17,000 law enforcement agencies, but it does not account for unreported crimes.
The NCVS, on the other hand, collects data from households on reported and unreported crimes, providing a more complete picture. Starting in 2021, a new system called the National Incident-Based Reporting System (NIBRS) will require states to report more detailed crime data. However, the actual number of crimes may still be underrepresented because not all crimes are reported due to various reasons such as victim's fear, shame, or distrust towards the police.