Summary of Traffic Stops Statistics
Rocky Mount 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 2018. 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 | RMPD |
|---|---|---|
| Stops | 24,980,776 | 96,728 |
| Traffic Safety Stops | 13,365,910 | 42,654 |
| Searches | 763,343 | 4,715 |
| Hits | 280,152 | 1,617 |
| Arrests | 500,040 | 3,422 |
| Arrest From Hit From Search | 105,784 | 588 |
| Consent Searches | 346,475 | 2,315 |
| Arrest From Hit From Consent Search | 20,759 | 63 |
| Probable Cause Searches | 264,963 | 1,829 |
| Arrest From Hit From Probable Cause Search | 54,326 | 378 |
| Percent Traffic Safety Stops | 53.50% | 44.10% |
| Search Rate Per Stop | 3.06% | 4.87% |
| Hit Rate Per Search | 33.48% | 31.26% |
| Arrest Rate Per Hit | 38.85% | 37.72% |
| Hit-and-Arrest Rate Per Search | 13.86% | 12.47% |
| Hit-and-Arrest Rate Per Probable Cause Search | 20.50% | 20.67% |
| Hit-and-Arrest Rate Per Consent Search | 5.99% | 2.72% |
| Arrest Rate Per Stop | 2.00% | 3.54% |
| Hit-and-Arrest Rate Per Stop | 0.42% | 0.61% |
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 2002-2018. Numbers range from approximately 3,000 (in 2006) to 14,000 (in 2017).
Figure 2 shows the total number of traffic stops by race and gender from 2002-2018. For example, in 2002, roughly 43% of total traffic stops were of black males, roughly 18% of stops were of white males, roughly 25% were of black females, and roughly 11% were of white females. White drivers’ share of those stopped decreased slightly over the timeframe. Black males made up a relatively consistent share of those stopped across the timeframe, while black females increased.
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 2002-2018. 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 2002-2018. 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. The rates of safety-related stops have also decreased across the time period for all race and gender categories.
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 2002-2018. 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 10% rate across the time period. Black males were searched at the highest rate in every year across the time period, ranging from just below 5% to about 17% across the time period. White males, the second-most searched group of drivers, were searched in 2 to 9% of stops. White and black female drivers were searched at the lowest 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 2002-2018. Across the board, arrest rates are consistently very low, at 8% or below for all categories across the time period. Black males are arrested at the highest rate every year, and their arrest rate ranges from about 2 to 8%. Arrest rates for the other race and gender categories range from 0 to 6%. From 2002 to 2007, white males were arrested at the second highest rate. Post-2007, however, white males were arrested at rates similar to or lesser than black females. White females were typically the least frequently arrested category.
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 2002-2018. The rates are very low for each category. All race and gender groups have rates of less than 2% across the time period. The rates for black males are in most cases the highest and typically range from 1 to 2%. For white males, contraband and arrest occur at rates typically ranging from 0.5 to 1%. Female drivers generally have the lowest rates of contraband and arrest, with certain exceptions such as in 2011, when white females surpassed white males. 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 2002-2018. 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, and is often between roughly 1.5 and 3. This means that black males are searched much more frequently than white males across the time period. The search rate ratio peaked at roughly 3 from 2008 to 2012. In the following years, the search rate ratio was typically just slightly above or below 2. The arrest rate ratio is also consistently above 1. The arrest rate ratio in the early years of the time period is relatively close to the search rate ratio of the same year. From 2008 to 2012, the disparity is greatest. During this period, black males are arrested at a greater rate than white males, but not to the degree that they are disproportionately searched. In the remainder of the time frame, the arrest rate ratio is higher than the search rate ratio. The difference between the two is highly variable, ranging from almost negligible to about a 6 point gap in 2018. This is the result of an extreme outlier for the arrest rate ratio in this year.
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 2002-2018. 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 about 0.4 to 3. The search rate ratio is often below 1, and only exceeds 2 in 2015 and 2018. The arrest rate ratio is typically between 1 and 2, with certain exceptions across the time period as well as an extreme outlier in 2009, where the arrest rate ratio is nearly 6. Over the entire period, the arrest rate ratio is more often than not higher than the search rate ratio, although there are various instances of the reverse being true. For 2008, arrest data is missing and therefore there is no arrest rate ratio for these years.
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. Stops occur at the highest rate late on Thursday, Friday, and Saturday night relative to the same time on the remaining days of the week. Search rates are lowest during the early morning hours of Thursday and Friday as compared to the rest of the week at the same time. Arrest rates are highest on the very early morning on Monday and Wednesday 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 decreases steadily in the early morning, reaching a low at 6AM. The number of traffic stops increases significantly from 6AM to 8AM. From 8AM until the late afternoon, traffic stops occur at a relatively stable rate. After 6PM, traffic stops increase in frequency and occur a at higher rate for the remainder of the day.
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 6AM. After 6AM, 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 6PM to 3AM. The rate then increases from 3AM to 7AM, and remains high for the remainder of the daytime hours, slowly beginning to decrease during the late afternoon. 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 from 5AM to 8AM. After 8AM, the rate of safety-related stops decreases until 10AM, then remains at a stable rate until 4PM. For the remainder of the day, the percent of safety-related stops decreases to its lowest point and remains at this level for the remainder of the day. Safety-related stops begin to occur more frequently in the early morning hours.
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 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. From midnight to 4AM, black males make up approximately 50 to 55% of total stops. By 7AM their share of stops decreases to about 25%. The rate then increases throughout the daytime, but is still at a lower percentage than during the nighttime hours. White males, in contrast, make up a relatively consistent share of the overall traffic stops throughout the day, at around 10% to 20%. Black females make up a relatively consistent share of traffic stops throughout the day, at around 30%. They briefly surpass black males from 7 to 8AM. White females consistently represent the lowest percentage of stops across the period. They see a slight uptick in their proportion of stops during the daytime hours.
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 majority of the day. In turn, this means that black males are more likely to be subjected to investigative stops that are not for moving violations. The disparity differs greatly based on the time of day. During the nighttime hours before midnight, all black drivers see a much lower percentage of safety-related stops relative to white drivers. During the daytime, however, black females are stopped for safety-related reasons at a rate comparable to white drivers. Non-safety-related stops are most common during the nighttime hours, when the percentage of safety-related stops is lowest. For 3AM to 6AM, stop data for white females is insufficient and is therefore 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 throughout the day, with the only exception coming at 1AM, when white males are searched at a slightly higher rate. The time of day does significantly influence the rate at which they are searched, however. Black males are more likely to be searched during a nighttime traffic stop relative to a daytime stop. Their search rate falls significantly in the early morning hours, and then steadily increases until the late afternoon. Other race and gender categories follow a similar trend, but black males are still significantly more likely to be searched than other drivers regardless of time of day. During the hours directly after midnight, when rates are highest, white males are searched at rates only slightly lower than black males, while both white and black females are searched at lower rates. Throughout the remainder of the day, white and black females are searched at very similar rates. 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. Throughout the day, black males are most likely to be arrested. All race and gender categories have increased rates of arrest in the early morning hours directly following midnight. Black males, however, have higher arrest rates than all other drivers for the remaining portion of the day. White males and all female drivers have similar rates throughout the remainder of the day. 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 2002-2018 time period. All officers displayed have over 100 traffic stops. 161 of the 209 officers included in the data have less than 500 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 2002-2018. The distribution includes officers with greater than 100 traffic stops. For the median officer, 74.82% of stops are of black drivers, while black people only make up 63.15% 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 85% of stops for a significant portion of officers. At the far right, the Figure shows that there are 35 officers whose mix of drivers stopped is more than 85% 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 2002-2018. In the first graph, which displays search rates for black males, the median officer has a search rate of 6.07%. For white male drivers, the median officer has a search rate of 3.07%. This indicates that the median officer in Rocky Mount 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 1.75, meaning that the median officer searches black male drivers at a higher rate than white male drivers.
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.