Summary of Traffic Stops Statistics
Kannapolis Police Department
The following report compiles and presents statistical summaries of traffic stops statistics drawn from the NC State Bureau of Investigation database to which each police agency reports their statistics each month. Data in this report cover the period of 2002 through 2020. The data exclude checkpoint stops because such stops are not recorded systematically. The data also include only the driver of the vehicle, excluding any passengers. Passenger information is generally recorded only in the event of an adverse outcome (e.g., search, arrest).
This report provides the following summary statistics:
First is a table providing summary statistics on numbers of stops, searches, contraband hits, and arrests, as well as relevant rates of these outcomes. This is followed by a series of graphics displaying department and officer level data.
| Summary of outcomes | State-wide | KPD |
|---|---|---|
| Stops | 24,980,776 | 151,081 |
| Traffic Safety Stops | 13,365,910 | 70,250 |
| Searches | 763,343 | 3,051 |
| Hits | 280,152 | 1,220 |
| Arrests | 500,040 | 2,405 |
| Arrest From Hit From Search | 105,784 | 536 |
| Consent Searches | 346,475 | 1,301 |
| Arrest From Hit From Consent Search | 20,759 | 105 |
| Probable Cause Searches | 264,963 | 614 |
| Arrest From Hit From Probable Cause Search | 54,326 | 88 |
| Percent Traffic Safety Stops | 53.50% | 46.50% |
| Search Rate Per Stop | 3.06% | 2.02% |
| Hit Rate Per Search | 33.48% | 37.04% |
| Arrest Rate Per Hit | 38.85% | 44.34% |
| Hit-and-Arrest Rate Per Search | 13.86% | 17.57% |
| Hit-and-Arrest Rate Per Probable Cause Search | 20.50% | 14.33% |
| Hit-and-Arrest Rate Per Consent Search | 5.99% | 8.07% |
| Arrest Rate Per Stop | 2.00% | 1.59% |
| Hit-and-Arrest Rate Per Stop | 0.42% | 0.35% |
Numbers at top of the table show raw values; numbers below are the percentages based on the numbers above.
Figure 1 shows the total number of stops per year from 2002-2020. Numbers range from approximately 5,500 (in 2007 and 2008) to just above 12,000 (in 2017). There is a drop associated with the global pandemic in 2020.
Figure 2 shows the total number of traffic stops by race and gender from 2002-2020. For example, in 2002, roughly 39% of total traffic stops were of white males, roughly 13% of stops were of black males, roughly 9% were of black females, and roughly 26% were of white females. White male drivers’ share of those stopped decreased over the timeframe. Both male and female black drivers, on the other hand, slightly increased as a proportion of total stops. White females’ share was roughly the same throughout the time period.
Figure 3. Percent of stops for “safety” purposes (speeding, stop sign, DUI, unsafe movement)
Figure 3 shows the percentage of traffic stops that are considered safety-related for each respective race and gender grouping, from 2002-2020. Safety-related spots are composed of stops due to speeding, stop sign violations, DWI, and unsafe movement. Stops for violations other than this are classified as non-safety related. These are composed of non-moving violations such as equipment violations and expired tags. For this reason, non-safety-related stops can be considered to be used as informal criminal investigations. Each race and gender grouping follows a similar trend from 2002-2020. White females and white males have a similar percentage of safety-related stops throughout the time period. Black drivers consistently had a lower percentage of their stops classified as safety-related as compared to white drivers. For the initial portion of the time period, there was a greater disparity between black males and females, however in the latter portion, the two groups had very comparable rates of safety-related stops.
Figure 4. Percent of stops resulting in a search, by race-gender category
Figure 4 shows the percent of traffic stops that result in a search for each respective race and gender grouping, from 2002-2020. The Figure indicates that most traffic stops do not result in a search. For all categories except black males, drivers were searched at less than a 6% rate across the time period. Black males were typically searched at higher rates, however the group’s search rate declined significantly over the time period. In the years 2002-2010, the search rate for black males ranged from roughly 3 to 8%. In the years post-2010, the search rate did not surpass 3%. White males were similarly searched at a decreasing rate across the time period, although this was still approximately only half as often as black males for a majority of the years. White and black female drivers experienced similar levels of search rates over the time period, with both groups typically being searched at a lower rate than white and black males.
Figure 5. Percent of stops resulting in arrest, by race-gender category
Figure 5 shows the percent of traffic stops that result in an arrest for each respective race and gender grouping, from 2002-2020. Across the board, arrest rates are consistently very low, at under 6% for all categories across the time period. Black males are arrested at the highest rate, however the group’s arrest rate significantly declined across the time period. From 2002 to 2012, the arrest rate for black males ranged from 2 to 6%. In the remainder of the time period, the arrest rate did not surpass 2%. White males followed a similar trend, with their arrest rate declining in a similar manner. Both white and black females typically had a lower arrest rate than males. In the latter half of the time period, specifically in the years 2016-2020, all race and gender categories had very comparable rates of arrest. No group of drivers had an arrest rate over 1% during this portion of the time period.
Figure 6. Percent of stops resulting in contraband and arrest, by race-gender category
Figure 6 shows the percent of stops that resulted in the discovery of contraband and an arrest for each respective race and gender grouping, from 2002-2020. The rates are very low for each category, at under 2%. For the first half of the time period, black males have the highest rate of contraband and arrest. However, their rates declined significantly in the latter half. White males followed a similar trend of decreasing contraband and arrest rates. From 2012 to 2020, all race and gender groups have extremely comparable rates of contraband and arrest. No group surpasses a 0.5% rate during this portion of the time period. Overall, for all race and gender categories, traffic stops are overwhelmingly unlikely to result in contraband and arrest, and this has become increasingly true across the timeframe.
Figure 7. Black-White Ratio of search rates and arrest rates, for males
Figure 7 compares the search rate and arrest rate of black males and white males from 2002-2020. The search rate ratio is the search rate of black males divided by the search rate of white males, while the arrest rate ratio is the arrest rate of black males divided by the arrest rate of white males. A search rate ratio of 1.0 would indicate that black and white males are both searched in an equal percentage of their respective traffic stops. This similarly applies for the arrest rate ratios. Across the time period, the search rate ratio ranges from about 1 to just above 4, and has great variation year-to-year. In a majority of years, the search rate ratio is above 1.5, meaning black males are typically searched much more frequently than white males. The arrest rate ratio also is consistently above 1, with an exception in 2020. There is also great variation for the arrest rate ratio, however it is typically lower than the search rate ratio. There are certain instances where it surpasses it, such as in 2010, 2012, and 2017, but typically there is still a significant gap between the two ratios. This means that in most years recorded, black males are arrested at a greater rate than white males, but not to the degree that they are disproportionately searched.
Figure 8. Black-White Ratio of search rates and arrest rates, for females
Figure 8 compares the search rate and arrest rate of black females and white females from 2002-2020. The search rate ratio is the search rate of black females divided by the search rate of white females, while the arrest rate ratio is the arrest rate of black females divided by the arrest rate of white females. A search rate ratio of 1.0 would indicate that black and white females are both searched in an equal percentage of their respective traffic stops. Across the time period, the search rate ratio typically ranges from about 0.2 to just below 2. There is a single extreme outlier in 2015, when the search rate ratio is approximately 4.9. The arrest rate ratio typically ranges from 0.6 to 2.1, with an exception in 2013, when it surpasses 3. Across the time period, the arrest rate ratio is typically above the search rate ratio for black females, but note that in many years the rates are quite comparable.
Figure 9. Summary of stops by hour over the week: Stops, percent safety-related, percent ending in citation, search, and arrest
Figure 9 displays the number of traffic stops, the percent of safety related stops, the percentage of drivers receiving a citation, the percentage of drivers searched, and the percentage of drivers arrested across the hours of the week. The Figure indicates that there is not much variation between the days of the week in regard to these measures, and instead shows that the variation is seen within the hours of the day. There are a few noticeable trends throughout the week, however. Search rates are highest during the early morning hours on Saturday as compared to the rest of the week at the same time. Arrest rates are highest immediately after midnight on Saturday and Sunday, as compared to the same time on other days.
Figure 10. Summary of stops by hour over the day: Stops, percent safety-related, percent ending in citation, search, and arrest
Figure 10 displays the number of traffic stops, the percent of safety related stops, and the percent of drivers searched, given a citation, and arrested by hour of day. There are a number of clear trends indicated in the Figure. The frequency of a traffic stop is lowest in the early hours of the morning, from around 4AM to 6AM. The number of traffic stops increases steadily until 8AM, at which point the frequency is quite stable until around 5PM. At 6PM, the frequency of stops drops sharply. Stops then increase to the previous level at 7PM, and this frequency is maintained until midnight, at which point traffic stops begin to decline into the early morning hours.
The percentages of drivers searched and arrested both have a similar trend across the time of day. Drivers are both searched and arrested at the highest rate in the few hours after midnight, and then these rates of search and arrest decrease dramatically from 3AM to 7AM. After 7AM, the rate of both search and arrest is at low percentages, and these rates then slowly increase for the remainder of the day.
The percentage of drivers receiving a citation follows an opposite trend of search and arrest rates. The rate of citations given is at its lowest from 8PM to 4AM. The rate then sharply increases from 4AM to 6AM, and remains high for the remainder of the day. The citation rate then decreases from 6PM to 8PM. The rate is significantly higher during daytime hours as compared to nighttime hours.
The percent of safety-related stops varies throughout the day, reaching its highest point at 6AM, and then slowly decreasing until noon. From noon to 2PM, safety-related stops increase slightly. After 2PM, the percentage of safety-related stops decreases for the remainder of the day, reaching a low point that is maintained through nighttime hours before the early morning increase.
Figure 11. Hourly breakdown of percent of stops by race-gender category
Figure 11 displays the share of overall stops represented by the respective race and gender categories by hour of day. The Figure indicates that white males make up the highest percentage of stops across the day, ranging between 30% and 40% throughout the day. The Figure also indicates that black males are significantly more likely to be stopped during the nighttime hours directly before and after midnight than they are to be stopped during the daytime. At 2AM, black males reach a high of about 22% of those that are pulled over, and by 7AM their share of stops decreases to about 10%, and stays at a lower proportion of stops throughout the daytime hours. Black females make up a consistent share of traffic stops throughout the day, at around 10%, White females see a significant uptick in their proportion of stops during the daytime hours, going from below 20% at 6AM to about 30% at 7AM. Rates for white females stay at this level for the remainder of the daytime hours, with their share of stops being just below rates for white males during this portion of the day.
Figure 12. Hourly breakdown of percent of stops related to traffic safety, by race-gender category
Figure 12 displays the percentage of stops that are for safety-related purposes for each race and gender category, by hour of the day. Safety-related purposes refer to traffic stops that are meant to prevent moving violations, and effectively keep the road safe. Stops that are not safety-related are often used for investigatory purposes, in which case the officer is generally seeking to conduct an informal criminal investigation of the driver. As evidenced in the Figure, black drivers are much less likely to be stopped for safety-related purposes than white drivers throughout the course of the day. In turn, this means that black drivers are more likely to be subjected to investigative stops that are not for moving violations. These stops are most common during the nighttime hours, when the percentage of safety-related stops is lowest. Throughout much of the day black drivers are significantly more likely to be stopped for a non safety-related purpose than white drivers. In the hours directly before and after midnight, black females see the lowest rate of safety-related stops. During the daytime hours, black males see the lowest rate of safety-related stops. Similarly, white females see a higher rate of safety-related stops during the daytime than white males, but during the nighttime, this is reversed.
Figure 13. Hourly breakdown of percent of stops resulting in search, by race-gender category
Figure 13 displays the percentage of traffic stops which result in a search for each race and gender category, by hour of the day. Black males are searched at the highest rate regardless throughout a majority of the day, but the time of day does significantly influence the rate at which they are searched. The rate of search during daytime hours is much lower than nighttime hours. From 3AM to 7AM, search rates of black males drop from 7% to about 0.5%. For the remainder of the daytime, search rates for black males range from 0.5 to 3%. This pattern applies for all of the gender and race categories. During daytime hours, however, black males are still significantly more likely to be searched than other race and gender categories. Throughout the entire day, white males are searched at a lower rate than black males, with the exception of 7AM, 3PM, and 5PM. Females, regardless of race, are typically searched at a lower rate than males. The Figure also indicates that a majority of stops do not result in a search regardless of race and gender category or time of day.
Figure 14. Hourly breakdown of percent of stops resulting in arrest, by race-gender category
Figure 14 displays the percentage of traffic stops which result in an arrest for each race and gender category, by hour of the day. For all categories, most drivers are more likely to be arrested during nighttime hours, specifically the hours directly after midnight. The main exception is black male drivers. This driver category’s arrest rate peak is maintained for a longer portion of the day, with rates being elevated until 6AM. For all other groups, stops are most likely to result in an arrest from approximately 2AM-4AM. For the remainder of the day, rates of arrest are below 2%. From 7AM to 2PM, black males are arrested at the highest rates. In the following portion of the day, black and white males have comparable rates of arrest, and females are still typically arrested at the lowest rate. The Figure also indicates that a large majority of stops do not result in an arrest regardless of race and gender category or time of day.
Figure 15. Number of stops by officer
Figure 15 displays the distribution of number of stops by officer across the 2002-2020 time period. All officers displayed have over 100 traffic stops. 115 of the 159 officers included in the data have less than 1000 traffic stops.
Figure 16. Percent black of drivers pulled over by officer
Figure 16 displays the percentage of stopped drivers that are black for individual officers, from 2002-2020. The distribution includes officers with greater than 100 traffic stops. For the median officer, 27.01% of stops are of black drivers, while black people only make up 21.7% of the population in the city. This means that a majority of officers are stopping black drivers at a rate disproportionate to their share of the population. This disparity between stop behavior and population data is often greater, with black drivers composing more than 35% of stops for a significant portion of officers. At the far right, the Figure shows that there are 18 officers whose mix of drivers stopped is more than 35% black.
Figure 17. Officer search rates by race
Figure 17 displays the search rates of individual officers for the given race and gender category. The criteria for an officer’s inclusion is 100 or more traffic stops, as well as at least 50 stops of the specified race and gender category, from 2002-2020. In the first graph, which displays search rates for black males, the median officer has a search rate of 1.69%. For white male drivers, the median officer has a search rate of 1%. This indicates that the median officer in Kannapolis is searching black males at a higher rate than they are searching white males.
Figure 18. Black-White Ratio of search rates by officer, for males
Figure 18 displays the distribution of black-white male search rate ratios across the officers which meet the criteria. The criteria for an officer’s inclusion is 50 traffic stops of both white males and black males, from 2002-2018. The “Black-white male search rate ratio” can be interpreted as an officer’s search rate of black male drivers divided by their search rate of white male drivers. An racially equitable outcome would therefore be 1, meaning that black and white male drivers are searched in an equal percentage of traffic stops. The median officer instead has a search rate ratio of 1.46, meaning that the median officer searches black male drivers at a higher rate than white male drivers. This is the lowest black-white male search rate ratio recorded in these reports (note that the rate ratio is still not racially equitable, however). There are certain officers that have search-rate ratios that are much higher than the median, with 5 officers searching black male drivers at 5 or more times the rate of white male drivers, and multiple officers searching black males at more than 10 times the rate.
Figure 19. Search rate versus hit rate by officer
Figure 19 presents the hit rates and search rates of individual officers who meet the criteria. As evidenced by the low correlation, there is great variability in both the propensity of individual officers to search drivers and their success in finding contraband. One might expect that when officers have a high search rate but a low hit rate, that their supervisors would advise them to adjust their search rate in order to avoid so many fruitless searches. Similarly, for officers with low search rates but high hit rates, one might expect supervisors to instruct them to conduct more searches because they are being too cautious. Such a learning process would generate relative consistent hit rates; where officers are too high, they would be advised to do more searches, and where too low, to conduct fewer. The Figure shows clearly that this is not happening. Search and hit rates range from low to high, with a very low correlation between the two. Certain officers search drivers at extremely high rates but have very low hit rates, meaning that their threshold of suspicion is likely too low. Other officers search at a much lower rate and have very high hit rates, showing that their threshold of suspicion may be too high. Overall, the Figure shows that officers are not gravitating towards a single common range of hit rates. This suggests that the department does not seem to hold its officers to a common standard of search rate success. Rather, each officer decides for him or herself how aggressive to be in searching, with virtually no guarantee that more searches will lead to lower hit rates, or that fewer searches will be targeted on those most likely to have contraband.