Crime rate is an extremely important statistic for many Americans, as it determines how comfortable and safe they feel in their homes and neighborhoods. It plays a large role in determining where Americans want to live, work, and raise their families. In fact, it is such an important issue that “around six-in-ten registered voters (61%) say violent crime is very important when making their decision about who to vote for in this year’s congressional elections”(Gramlich). Because of crime rate’s significance in today’s society, it is important to understanding how it has changed in the past, and what that may mean for the future. With this being said, through this project, I hope to understand, generally, how crime rate (and crime rate per population) have changed over time. I also hope to better understand what types of crime have increased the most/least, as well as where crime has increased/decreased. In this project, I will mainly be focusing on property crime rate and violent crime rate, as the summation of these two values do a good job of estimating the total crime rate. In this case, property crime includes the offenses of burglary, larceny, and motor vehicle theft, while violent crime includes robbery, rape, homicide, and aggressive assault. First, I will take a look broadly at how crime has changed over time (in the past 40 years). I will then dive deeper into how crime has changed in the past decade, then in the past year. I hope that with this specified search, my visualizations will give a good picture of how crime and time relate, with an emphasis on recent years.

United States Crime Rate in the past 40 years

The above graphic displays the violent crime rate in America from 1979 to 2022. Despite the fairly large spike in the early 1990s, the violent crime rate appears to have stayed generally the same. From the early 1990s to 2022, violent crime in America seems to have decreased.

The property crime rate does seem to show a generally decreasing trend from 1978 to 2022, but it has been decreasing at a much larger rate since a bit before 2010. So far, it appears as though, generally, crime rate has decreased a bit since the 1980s, and especially since around the 1990s. While the general crime rate is good to understand, it may be important to take change in population into consideration, as it is generally known that the more people live in an area, the more crimes will be committed. We will look at Crime Rate per Population (specifically for property and violent crime) next.

Apart from the stark increase in both property and violent per population crime rate in the early 1990s, we can see a general decrease it both types of crime rates per population overtime. When population is not considered, crime seems to have decreased slightly; when population is taken into account, this decrease is much more drastic. Since the relationship between time and crime seems to depends on population, this relationship will be further investigated moving forward.

Relationship between Crime Rate and Population over time

To start, it is important to note that the specific dots in these graphs represent different US states; the size of the points represent the given state’s population. Through time, the slope of the relationship between population and crime seems to have decreased for both property crime and violent crime. This means that the total crime rate (the combination of violent and property crime rate) increases slightly less for an increase in population, as time goes on. This result makes sense, as before, we claimed that the general decrease in crime rate over time is more extreme when population is taken into account.

Now that we have a general understanding of how both crime rate, and crime rate per population, have changed over time, we will dig a bit deeper into specific offences, and how they have changed over the past 40 or so years. The following Shiny Application allows you to explore the following specific offences: burglary, larceny, motor vehicle theft, robbery, rape, homicide, and aggressive assault.

Shiny App Link: https://ellathomasson.shinyapps.io/shiny/

Through this app, we can see that most specific offences appear to have generally decreased over the past 40 years. Burglary seems to have decreased very steadily over this period, while rape has barely decreased at all. We can also take a look at crime rate in specific states. Below is a shiny application that allows you to explore the change in crime rate for different US states over time.

Shiny App Link: https://ellathomasson.shinyapps.io/shiny_state/

In this app above, it is important to note that the x-axis for the graphics depicted does not start as 0. This is because, on a per state bases, the crime rate does not change a ton over time. The graphic is zoomed in so that small trends could be recognized. As you can probably tell, the change in violent crime rate per population over time for specific states appears to vary vastly. In general, it appears as though most states’ per population violent crime rates have decreased. We can also look at these state wide trends over time in a broader way, through a map. Below is a screenshot of a Tableau dashboard showing how both violent and property crimes have changed over time. This dashboard also shows the change in per population crime for both of these variables.

The maps shown above are animated on Tableau to show the change in crime rate and crime rate per population over time. From these maps, we can see that, when population is not taken into account, it is much harder to see the change in crime for individual states. When population is taken into account, the small changes in crime over time (especially for property crime) are more noticeable. As previously mentioned, for the shiny application, the scatter plot showing the change in crime rate over time for states had to be zoomed in because the differences on a year to year basis were not very large for specific states. This point is highlighted in this graphic, as very little change is seen year to year. However, over the full 40 years, we can see a small decrease in both crime rates for the majority of states.

To conclude this section, it appears that over the past 40 years, total crime has decreased slightly, while total crime per population has decreased at a larger rate. This could very possibly be because of the observed change in relationship between crime and population over time. More specifically, we saw that most crime rates for specific offences decreased over the past 40 years, with the exception of rape, which appeared to generally stay consistent. On a statewide level, it is difficult to see specific per year changes in crime. The general decrease in crime rate observed was not caused by one large increase in one state, but by the combination of small decreases in most states.

United States Crime Rate in the past 10 years

We can also look at the change in crime rate over the past decade. The graphic below displays the percent change in the number of arrests for specific crimes from 2013 to 2022.

From this graphic, we can see that, over the past decade, the number of arrests for most offenses has decreased. We can see that drunkenness, suspicion, liquor laws, gambling, and prostitution have decreased by the largest percent. The total number of arrests has decreased by around 37% over this decade! The bars outlined in green represent the offenses with the largest change in number of arrests between 2013 and 2022. These include: larceny, drug violations, driving under the influence, and drunkenness. We will dive a bit deeper into these highlighted offences.

From this graphic, we easily compare the number of arrests for the different offenses across the years. Again, these are the four offenses that had the largest change in number of arrests from 2013 to 2022. From this graphic, we can see that drunkenness has decreased from around 320,000 arrests, to less than 14,500 arrests. This is a very extreme decrease.

To conclude this section, it appears as though there has been a general decrease in number of arrests from 2013 to 2022. Again, the average percent decrease across all offenses throughout the decade has been around 37%. Additionally, a decrease in arrests was observed for just about every single individual offense. The specific offenses that had the greatest change in number of arrests were drug abuse, larceny, driving under the influence, and drunkenness. It is interesting that 3 out of the top 4 changes in number of arrests had to do with alcohol/drugs. This is an interesting and possibly notable trend.

United States Crime Rate in the past year

Next, we will take a closer look at how crime has changed in the past year (from 2022 to 2023).

The above graph displays the average crime rate for both 2022 and 2023 based on city population. As we can see, the average crime for 2022 seems to be generally lower than the average crime for 2023 for all city populations. However, we can see that, as the city population increases, there appears to be a larger decrease in average crime rate for these locations. This result suggests that recently, while all cities have experienced a decrease in crime, the larger cities have generally experienced the higher decrease. Cities with 1,000,000 residents or more experienced a crime decrease of around 11%! This is a very extreme and surprising one year percent decrease.

The above graphic shows the percent decrease in crime rate from 2022 to 2023 for the different regions. The Western region had a 6% decrease, the Southern region has a 5% decrease, the Midwestern region experienced a 7% decrease, and the Northeastern region experienced a 8% decrease. Based on this plot, we can see that each region has experienced some sort of decrease in crime rate. We can also see that the Northeastern region experienced the greatest decrease, while the Southern region experiences the smallest decrease. This graph gives us a good understanding of how the understood decrease in United States crime rate over the past year was distributed across the regions.

Conclusion

In this study, we set out to better understand how crime rate, and crime rate per population, have changed over time, with an emphasis on recent years. We learned that the total crime rate in America has generally decreased over time, especially when population is taken into account. This was proven through an exploration specific offense’s and specific state’s change in crime over time. Generally, most specific offenses and specific states experienced a decrease in crime over time.

Looking more specifically into the past decade, we learned that crime has decreased by around 37% from 2013 to 2022. We were able to better understand specific offences that increased/decreased the most. When taking a closer look into the past year (2022 to 2023), we learned that total crime has again decreased, especially in cities with a large population, and especially in the Northeastern region of America.

This study proved that crime rate has generally decreased over time, and it gave a well rounded view on how it decreased over different time periods.

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