Changes in Crime Rates Over Time

Police statistics on known offenders and victimization surveys reveal different patterns with respect to changes in crime rates over time. Crime rates based on police data in the United States increased dramatically between 1960 and 1990, and they have declined noticeably since the mid-1990s. These official crime trends are similar for both violent and property crimes. Victimization surveys in the United States, however, indicate crime trends that are qualitatively different from those based on police data. Specifically, violent victimization rates remained fairly stable between the early 1970s and mid-1990s, before declining in a fashion similar to the trend revealed in the UCR data. Contrary to the pattern of a rise and fall in property crimes shown in the UCR data, victimization surveys indicate that property crime has exhibited a rather continuous decline since the mid-1970s.

The contradictions in crime trends based on UCR and NCVS data are explained in large part by differences across these methods in their coverage of crimes, rules for counting crime incidents, and the population base from which rates are computed. Unfortunately, the limitations that surround both these measures of crime make it difficult to have strong confidence in either of the apparent trends. Under these conditions, it is unclear whether, or in what way, crime rates in the United States have actually changed in the last four decades.