Summary of Traffic Stops Statistics
Apex 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 | APD |
|---|---|---|
| Stops | 24,980,776 | 148,691 |
| Traffic Safety Stops | 13,365,910 | 74,263 |
| Searches | 763,343 | 4,318 |
| Hits | 280,152 | 1,729 |
| Arrests | 500,040 | 2,577 |
| Arrest From Hit From Search | 105,784 | 728 |
| Consent Searches | 346,475 | 1,841 |
| Arrest From Hit From Consent Search | 20,759 | 136 |
| Probable Cause Searches | 264,963 | 1,966 |
| Arrest From Hit From Probable Cause Search | 54,326 | 461 |
| Percent Traffic Safety Stops | 53.50% | 49.94% |
| Search Rate Per Stop | 3.06% | 2.90% |
| Hit Rate Per Search | 33.48% | 35.73% |
| Arrest Rate Per Hit | 38.85% | 44.48% |
| Hit-and-Arrest Rate Per Search | 13.86% | 16.86% |
| Hit-and-Arrest Rate Per Probable Cause Search | 20.50% | 23.45% |
| Hit-and-Arrest Rate Per Consent Search | 5.99% | 7.39% |
| Arrest Rate Per Stop | 2.00% | 1.73% |
| Hit-and-Arrest Rate Per Stop | 0.42% | 0.49% |
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 4,000 (in 2004) to 14,000 (in 2019).
Figure 2. Percent of stops by race-gender category
Figure 2 shows the total number of traffic stops by race and gender from 2002-2020. For example, in 2002, roughly 42% of total traffic stops were of white males, roughly 11% of stops were of black males, roughly 6% were of black females, and roughly 26% were of white females. Each race and gender category’s respective share of stops was stable across the time period, with no significant changes for any driver groups.
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 typically had the highest percentage of safety-related stops throughout the time period. Black males consistently had the lowest percentage of their stops classified as safety-related as compared to white drivers. Throughout much of the time period, black females and white males had comparable rates of safety-related stops, with a key exception from 2017-2020, when both groups converged with their respective race.
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, ranging from 4 to just above 12% across the time period. This is significantly more often as the second most searched group, white males, who were searched in 2 to 6% of stops. White and black female drivers experienced similar levels of search rates over the first half of the time period, with both groups being searched at a lower rate than white and black males. In the latter half of the time period, white males and black females had very comparable search rates.
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 5% for all categories across the time period, with the exception of black males in 2011. Black males are arrested at the highest rate, ranging from 1 to just above 5%, although the rate is typically between 2 to 4%. Arrest rates for the other race and gender categories typically range from 0 to 3%, with the sole exception being in 2011 when black females were arrested at about a 4% rate. This was the only instance of an arrest rate above 2% for black females. White males are typically the group with the second highest arrest rate.
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. White males, white females, and black females all have rates of less than 1% across the time period with very little variation. The rates for black males have great variation, and range from, from 0.2% of stops in 2008 to 2.5% of stops in 2017 resulting in contraband and arrest. Note that 2017 is the only instance where the rate of contraband and arrest surpassed 2% for black males, however. Overall, for all race and gender categories, traffic stops are overwhelmingly unlikely to result in contraband and arrest.
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 is consistently above 1.5, with a few exceptions. This means that black males are searched much more frequently than white males across the time period. The search rate ratio peaked at about 3.4 in 2017, and typically ranged from 1.5 to 3.0. The arrest rate ratio also is consistently above 1. For many of the years across the time period, there is not a great disparity between search rate ratio and arrest rate ratio. In certain instances one ratio is still significantly higher than the other, but this is rarer than in other comparable departments.
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 ranges from 0.6 to just below 4.0. The arrest rate ratio ranges from 0.5 to 3.5. Both ratios fluctuate greatly on a yearly basis, and in many cases move together. There are certain instances of an extreme disparity between the two, such as in 2015, when the search rate ratio was 4.0 and the arrest rate ratio was below 1.5.
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 and arrest rates are both slightly higher in the very early morning (directly after midnight) on Fridays, Saturdays, Sundays, and Tuesdays, 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 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 Figure 10. 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 dramatically until 8AM, at which the frequency is similar until around 4PM. Stop frequency drops sharply at 5 and 6PM, bit then increases again until 9PM. At 9PM, the frequency of stops begins to drop again until the low point in the early morning.
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 until 8AM. After 8AM, the rate of both search and arrest is at extremely 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 9PM to 5AM. The rate then sharply increases at 6AM, and remains high for the remainder of the day, until it begins to decrease at 5PM. 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 5AM, and then generally decreasing until 9PM, with a significant amount of variation throughout the middle of the day. Safety-related stops then are maintained at a low frequency until the early morning, at which point they increase sharply to the early morning high.
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, at roughly 40% throughout the day. The figure also indicates that black males are more likely to be stopped during the nighttime hours directly before and after midnight than they are to be stopped during the daytime. At 4AM, black males reach a high of 22% of those that are pulled over, and by 7AM their share of stops decreases to 10%, and stays at a lower proportion of stops throughout the daytime hours. Black females make up a relatively consistent share of traffic stops throughout the day, at around 9%. White females see a significant uptick in their proportion of stops during the daytime hours, going from below 20% during the nighttime hours to almost 30% during the daytime.
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 males are much less likely to be stopped for safety-related purposes than other 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. The rate at which these stops occur does not change dramatically based on the time of day, as it does in many similar cities detailed in these reports. For much of the daytime, white females have the highest rate of safety-stops, while black females and white males have a similar percentage of stops classified as such. From 5AM to 6AM, both black and white females have insufficient data and therefore are not displayed.
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 across almost the entire day (with the exception of 2AM and 3AM), but the time of day does significantly influence the rate at which they are searched. Search rates of black males are relatively lower for much of the daytime, and begin to increase in the late afternoon and early evening hours. Stops are highest during the hours directly before and after midnight. All groups see increased search rates during the nighttime hours. During the early morning hours, white males are searched at comparable levels to black males. However, during the daytime hours, their search rate is quite comparable to female drivers. White and black females are searched at similar levels throughout the entire day. 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, drivers are more likely to be arrested during nighttime hours, specifically the hours directly after midnight. White males are the most likely to be arrested during these hours. For the remainder of the daytime hours, black males are the most likely to be arrested, but the arrest rate does not typically surpass 4%. For most of the daytime hours, white males and all females have comparable arrest rates. During the late afternoon and early evening, rates begin to increase for all race and gender categories. 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. 114 of the 153 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, 20.62% of stops are of black drivers, while black people only make up 7.3% 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 30% of stops for a significant portion of officers. At the far right, the Figure shows that there are 8 officers whose mix of drivers stopped is more than 30% 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, the median officer has a search rate of 4.96%, meaning that black male drivers are searched in 4.96% of traffic stops. A significant portion of officers have search rates that are much higher than this median value, meaning that searches occur more often for certain officers in traffic stops involving black males. For white male drivers, the median officer has a search rate of 1.75%. This indicates that the median officer in Apex 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 2002-2020. 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 1.97, meaning that the median officer searches black male drivers at a higher rate than white male drivers. A significant number of officers have search-rate ratios that are much higher than the median, with some searching black male drivers at 3 or more times the rate of white male drivers, and a single officer searching black males are 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.