NHTSA’s National Center for Statistics and Analysis 1200 New Jersey Avenue SE., Washington, DC 20590

DOT HS 810 921 February 2008

Traffic Safety Facts

Research Note

States With Primary Enforcement Laws Have 

Lower Fatality Rates (Updated)†

Summary

This Research Note compares the percentage of unrestrained passenger vehicle occupant fatalities and fatality rates between States that have primary seat belt use 

laws and States that do not have them for the most 

recent years, 2005 and 2006. Besides having a smaller 

percentage of passenger vehicle occupant fatalities 

who were unrestrained, the fatality rates in primary 

enforcement States (PE States) were much lower than 

for all other States (non-PE States). The total passenger 

vehicle occupant fatality rate per 100 million VMT for 

non-PE States (1.06) is 9 percent higher than that for 

the PE States (0.97). The total passenger vehicle occupant fatality rate per 100,000 population for the non-PE 

States (11.78) is 15 percent higher than that for the PE 

States (10.20).

Compared with a previous study,† the difference 

between non-PE States and PE States during 2005 and 

2006 is smaller than that between 2000 and 2004 (during 

2000-2004, the fatality rate per 100 million VMT and the 

fatality rate per 100,000 population for non-PE States is 

17 percent and 23 percent higher than that for the PE 

States, respectively).

Introduction 

Seat belt use is the most effective countermeasure available to passenger vehicle occupants to prevent fatalities and serious injuries in highway motor vehicle traffic crashes. In order to encourage the use of seat belts, 

most States have enacted seat belt laws. The enacted 

seat belt laws vary widely, but these laws generally can 

be classified as primary or secondary. The primary laws 

permit law enforcement officers to stop a vehicle and 

issue a citation for a seat belt violation, even if this is the 

†This is an update of States with Primary Enforcement Laws 

Have Lower Fatality Rates, Cejun Liu, Tonja Lindsey, Chou-Lin 

Chen, & Dennis Utter. NHTSA Research Note, DOT HS 810 

557, February 2006. Washington, DC: National Highway 

Traffic Safety Administration.

only violation the officers notice. The secondary laws 

allow the officers to issue seat belt citations to motorists 

only after they stop the drivers for other violations. 

Twenty-five jurisdictions in the 50 States and the 

District of Columbia had primary enforcement laws 

in 2006. These primary jurisdictions are: Alabama, 

Alaska, California, Connecticut, Delaware, District of 

Columbia, Georgia, Hawaii, Illinois, Indiana, Iowa, 

Kentucky, Louisiana, Maryland, Michigan, Mississippi, 

New Jersey, New Mexico, New York, North Carolina, 

Oklahoma, Oregon, South Carolina, Tennessee, Texas, 

and Washington. The category “All Other States” in the 

tables below includes those that have secondary laws 

or have no adult seat belt use law (New Hampshire). 

If a State converted from a secondary to a primary 

law in the middle of a year within 2005 and 2006, it 

was included in the appropriate group except for the 

year that the law was upgraded, in which case it was 

excluded al­together. Namely, data for South Carolina 

in 2005, Alaska, Kentucky, and Mississippi in 2006 was 

ex­cluded. This analysis also excludes fatalities to infants 

and toddlers, up to age 4, since most States, including 

secondary States, have child restraint laws that typically call for primary enforcement. 

State seat belt use surveys, conducted in accordance 

with Section 157, Title 23, of the U.S. Code, show that the 

observed daytime rate of seat belt use is in general higher in PE States as compared to the non-PE States. Other 

studies have shown that the seat belt use rates in States 

that upgrade to primary seat belt laws typically increase 

7 to 9 percentage points the following years, and a significant number of fatalities could be reduced if all States 

with secondary laws converted to primary laws.‡

The purpose of this study is to assess the advantage of 

primary laws by comparing the passenger vehicle (PV) 

‡ See NHTSA Research Note, DOT HS 810 557, February 

2006, and references therein. 
NHTSA’s National Center for Statistics and Analysis 1200 New Jersey Avenue SE., Washington, DC 20590



restraint use of fatally injured occupants and the fatality rates with respect to two exposure measures, Vehicle 

Miles Traveled and population between PE States and 

non-PE States for the most recent years, 2005–2006. 

Results

Restraint use

Table 1 shows that the percentage of passenger vehicle occupant fatalities who were unrestrained in the 

PE States (50%) is much lower than that in the non-PE 

States during 2005 and 2006 (63%). As for the differences among age groups, the unrestrained percentages 

between PE States and the non-PE States are: 51 versus 

62 for the 5 to 15 age group; 55 versus 72 for the 16 to 

20 age group; and 48 versus 61 for the 21 and older age 

group. It also shows the unrestrained percentage for 

the 16 to 20 age group is higher than that for the other 

two age groups in both the PE and non-PE States.

Table 

Passenger Vehicle Occupant Fatalities by Age and Restraint Use in States With Primary Seat Belt Use Laws and All Other States, 2005-2006

Occupant Age

Restraint Use

Restrained Unrestrained

Number % Number % Total

Primary Seat Belt Use Law States

5-15 576 49 606 51 1,182

16-20 2,279 45 2,768 55 5,047

21+ 13,173 52 12,371 48 25,544

Total 16,028 50 15,745 50 31,773

All Other States

5-15 299 38 491 62 790

16-20 1,023 28 2,612 72 3,635

21+ 7,029 39 10,994 61 18,023

Total 8,351 37 14,097 63 22,448

•	 Occupants with unknown age and unknown restraint use are not included in the table

•	 For the fatality counts, if the law changed in the middle of a year, that State was excluded from that year altogether in both State groups, but included in other years in

appropriate group

Source: Fatality Analysis Reporting System (FARS) 2005 Final and 2006 ARF Files

Fatality Rate per 100 Million VMT 

Table 2 shows the passenger vehicle occupant fatalities, 

total VMT, and passenger vehicle occupant fatality rate 

per 100 million VMT for both the PE and non-PE States 

during 2005 and 2006. The fatality rates are higher in the 

non-PE States when compared to those in the PE States. 

Table 2 shows the passenger vehicle occupant fatality 

rate for the non-PE States (1.06) is 9 percent higher than 

that for the PE States (0.97). Since the State level VMT 

estimates cannot be broken out by either vehicle type 

or age, the fatality rate by VMT was examined only as 

a whole.

Table 

Passenger Vehicle Occupant Fatalities, Total VMT, and Passenger Vehicle Occupant Fatality Rate per 100 Million VMT in States With Primary 

Seat Belt Use Laws and All Other States, 2005–2006

Year

Fatalities in States † Total VMT ‡ Fatality Rate per 100 Million VMT

Primary All Other States Primary All Other States Primary All Other States

2005 17,076 13,129 1,755,321 1,184,675 0.97 1.11

2006 17,475 11,032 1,815,517 1,104,392 0.96 1.00

Total 34,551 24,161 3,570,838 2,289,067 0.97 1.06

•	 Fatalities include all occupants 5 and older, regardless of the restraint use (used, not used, and unknown).

•	 For the fatality counts and VMT, if the law changed in the middle of a year, that State was excluded from that year altogether in both State groups, but included in other years

in the appropriate group.

Source: 

† Fatality Analysis Reporting System 2005 Final and 2006 ARF Files

‡ Federal Highway Administration


NHTSA’s National Center for Statistics and Analysis 1200 New Jersey Avenue SE., Washington, DC 20590

Fatality Rate per 100,000 Population

Table 3 shows the passenger vehicle occupant fatality rate per 100,000 population by age group in the PE 

States and the non-PE States during 2005 and 2006. The 

overall fatality rates are higher in the non-PE States, as 

compared to those in the PE States in every age group: 

2.34 versus 2.72 for the 5 to 15 age group; 21.27 versus 

25.76 for the 16 to 20 age group; and 10.78 versus 12.26 

for the 21 and older age group. In both the PE and nonPE States, the fatality rate for the 16 to 20 age group is 

more than nine times the rate for the 5 to 15 age group 

and two times the rate for the 21 and older age group. 

Thus, both the population-based fatality rate shown in 

Table 3 and the VMT-based fatality rate shown in Table 

2 clearly show the same pattern of lower fatality rates 

for States having primary seat belt use laws. 

Table 

Passenger Vehicle Occupant Fatalities, Population, and Passenger Vehicle Occupant Fatality Rate per 100,000 Population by Age in States With 

Primary Seat Belt Use Laws and All Other States, 2005-2006

Occupant Age Year

Fatalities in States † Population in States ‡ Fatality Rate per 100,000 Population

Primary All Other States Primary All Other States Primary All Other States

5-15

2005 672 474 27,649,561 16,547,971 2.43 2.86

2006 637 394 28,172,404 15,316,554 2.26 2.57

Total 1,309 868 55,821,965 31,864,525 2.34 2.72

16-20

2005 2,721 2,085 12,731,185 7,825,832 21.37 26.64

2006 2,807 1,832 13,261,571 7,379,113 21.17 24.83

Total 5,528 3,917 25,992,756 15,204,945 21.27 25.76

21+

2005 13,683 10,570 126,227,941 81,242,928 10.84 13.01

2006 14,031 8,806 130,811,174 76,788,344 10.73 11.47

Total 27,714 19,376 257,039,115 158,031,272 10.78 12.26

Total 34,551 24,161 338,853,836 205,100,742 10.20 11.78

•	 Fatalities include all occupants 5 and older, regardless of the restraint use (used, not used, and unknown).

•	 For the fatality counts and population, if the law changed in the middle of a year, that State was excluded from that year altogether in both State groups, but included in other

years in appropriate group.

Source: 

† Fatality Analysis Reporting System 2005 Final and 2006 ARF Files

‡ U.S. Bureau of Census

Fatality Rate per 100,000 Population by State 

in 2006 

Table 4 shows the detailed information of passenger 

vehicle occupant fatality rate per 100,000 population by 

age group and State in 2006. States with primary seat 

belt use laws at the end of 2006 are highlighted in the 

table. Alaska, Kentucky, and Mississippi upgraded to 

primary enforcement in the middle of 2006, and were 

excluded in the analysis in Tables 1 to 3 for the year 

2006. Total fatality rates are higher in the non-PE States, 

compared to those in the PE States in every age group.

Conclusions 

Seat belt use can reduce fatalities and injuries in highway traffic crashes. Increased use of seat belts would 

save more lives when motor vehicle crashes inevitably 

occur. In this study, data shows that the percentage of 

passenger vehicle occupant fatalities that were unrestrained in the PE States is much lower than that in the 

non-PE States, 50 percent versus 63 percent during 2005 

and 2006. The total passenger vehicle occupant fatality rate per 100 million VMT for non-PE States (1.06) 

is 9 percent higher than that for the PE States (0.97). 

The total passenger vehicle occupant fatality rate per 

100,000 population for the non-PE States (11.78) is 15 

percent higher than that for the PE States (10.20). Studies demonstrate that the crash fatalities could be prevented if the non-PE States (those with secondary laws 

and with no adult seat belt use laws) were upgraded 

to States with primary laws. Converting these States 

to primary enforcement laws is a straightforward way 

to save a significant number of lives in highway motor 

vehicle traffic crashes in the United States.
NHTSA’s National Center for Statistics and Analysis 1200 New Jersey Avenue SE., Washington, DC 20590



Table 

Passenger Vehicle Occupant Fatality Rate per 100,000 Population by Age in States in 2006

State

Fatalities Population Fatality Rate per 100,000 Pop

5-15 16-20 21+ Total ‡ 5-15 16-20 21+ Total 5-15 16-20 21+ Total

AL 44 153 763 960 682,080 323,014 3,294,559 4,299,653 6.45 47.37 23.16 22.33

AK 5 5 35 45 109,136 51,114 460,032 620,282 4.58 9.78 7.61 7.25

AZ 47 141 647 835 970,352 417,425 4,298,050 5,685,827 4.84 33.78 15.05 14.69

AR 17 90 388 495 417,425 193,125 2,007,431 2,617,981 4.07 46.60 19.33 18.91

CA 95 460 2,150 2,705 5,766,967 2,696,067 25,316,496 33,779,530 1.65 17.06 8.49 8.01

CO 18 66 278 362 697,303 315,873 3,399,132 4,412,308 2.58 20.89 8.18 8.20

CT 2 41 157 200 513,915 246,341 2,541,722 3,301,978 0.39 16.64 6.18 6.06

DE 1 16 84 101 123,047 60,851 612,886 796,784 0.81 26.29 13.71 12.68

DC 0 5 13 18 67,186 43,020 436,376 546,582 0.00 11.62 2.98 3.29

FL 62 301 1,646 2,009 2,417,822 1,137,350 13,411,867 16,967,039 2.56 26.47 12.27 11.84

GA 33 183 1,066 1,282 1,473,667 665,721 6,522,419 8,661,807 3.73 27.49 16.34 14.80

HI 5 16 73 94 176,826 83,536 937,815 1,198,177 2.83 19.15 7.78 7.85

ID 9 35 165 209 235,522 107,401 1,010,579 1,353,502 3.82 32.59 16.33 15.44

IL 32 164 707 903 1,956,839 922,570 9,064,956 11,944,365 1.64 17.78 7.80 7.56

IN 20 118 509 647 962,295 448,724 4,471,412 5,882,431 2.08 26.30 11.38 11.00

IA 8 52 262 322 432,046 222,459 2,135,525 2,790,030 1.85 23.38 12.27 11.54

KS 12 53 281 346 419,688 206,249 1,944,038 2,569,975 2.86 25.70 14.45 13.46

KY 19 97 577 693 606,711 276,460 3,047,152 3,930,323 3.13 35.09 18.94 17.63

LA 26 109 601 736 659,867 323,373 3,003,153 3,986,393 3.94 33.71 20.01 18.46

ME 6 28 106 140 172,972 88,636 989,721 1,251,329 3.47 31.59 10.71 11.19

MD 7 74 368 449 827,204 399,112 4,021,212 5,247,528 0.85 18.54 9.15 8.56

MA 5 53 237 295 885,902 453,079 4,710,349 6,049,330 0.56 11.70 5.03 4.88

MI 27 98 635 760 1,535,515 734,067 7,187,866 9,457,448 1.76 13.35 8.83 8.04

MN 9 66 282 357 759,854 371,502 3,690,495 4,821,851 1.18 17.77 7.64 7.40

MS 30 101 620 751 460,446 220,817 2,019,820 2,701,083 6.52 45.74 30.70 27.80

MO 37 172 660 869 859,379 408,546 4,188,036 5,455,961 4.31 42.10 15.76 15.93

MT 5 28 177 210 131,930 66,647 688,139 886,716 3.79 42.01 25.72 23.68

NE 19 43 160 222 265,137 131,743 1,243,786 1,640,666 7.17 32.64 12.86 13.53

NV 16 34 251 301 381,685 149,425 1,780,831 2,311,941 4.19 22.75 14.09 13.02

NH 1 14 83 98 185,384 92,477 963,459 1,241,320 0.54 15.14 8.61 7.89

NJ 9 58 300 367 1,281,848 577,634 6,306,084 8,165,566 0.70 10.04 4.76 4.49

NM 20 44 268 332 306,999 146,921 1,358,710 1,812,630 6.51 29.95 19.72 18.32

NY 18 153 668 839 2,748,646 1,398,151 13,938,918 18,085,715 0.65 10.94 4.79 4.64

NC 47 167 949 1,163 1,298,619 608,877 6,337,899 8,245,395 3.62 27.43 14.97 14.10

ND 7 18 64 89 87,292 53,394 455,625 596,311 8.02 33.71 14.05 14.93

OH 29 142 732 903 1,701,967 804,629 8,236,675 10,743,271 1.70 17.65 8.89 8.41

OK 27 90 466 583 536,133 253,080 2,535,281 3,324,494 5.04 35.56 18.38 17.54

OR 14 56 274 344 522,131 242,546 2,705,421 3,470,098 2.68 23.09 10.13 9.91

PA 26 167 885 1,078 1,723,277 900,333 9,092,324 11,715,934 1.51 18.55 9.73 9.20

RI 2 8 37 47 146,122 85,031 774,496 1,005,649 1.37 9.41 4.78 4.67

SC 21 108 623 752 630,017 313,095 3,094,656 4,037,768 3.33 34.49 20.13 18.62

SD 5 24 118 147 116,244 58,764 552,083 727,091 4.30 40.84 21.37 20.22

TN 35 161 771 967 875,423 396,110 4,369,018 5,640,551 4.00 40.65 17.65 17.14

TX 134 393 1,979 2,506 3,861,207 1,723,025 15,998,354 21,582,586 3.47 22.81 12.37 11.61

UT 7 42 161 210 461,168 202,682 1,638,412 2,302,262 1.52 20.72 9.83 9.12

VT 2 13 57 72 82,361 47,060 461,708 591,129 2.43 27.62 12.35 12.18

VA 23 132 594 749 1,087,333 529,843 5,516,743 7,133,919 2.12 24.91 10.77 10.50

WA 12 88 345 445 933,927 433,277 4,620,436 5,987,640 1.28 20.31 7.47 7.43

WV 8 45 244 297 236,659 118,551 1,358,296 1,713,506 3.38 37.96 17.96 17.33

WI 13 97 428 538 800,594 402,154 4,004,994 5,207,742 1.62 24.12 10.69 10.33

WY 9 20 125 154 73,182 37,194 371,075 481,451 12.30 53.77 33.69 31.99

National 1,085 4,842 24,069 29,996 44,665,251 21,189,075 213,126,522 278,980,848 2.43 22.85 11.29 10.75

Primary 637 2,807 14,031 17,475 28,172,404 13,261,571 130,811,174 172,245,149 2.26 21.17 10.73 10.15

Others 394 1,832 8,806 11,032 15,316,554 7,379,113 76,788,344 99,484,011 2.57 24.83 11.47 11.09

PR 6 33 183 222 648,165 293,957 2,734,050 3,676,172 0.93 11.23 6.69 6.04

•	 States with primary seat belt use laws at the end of 2006 are highlighted in the table. Upgraded States in the middle of 2006 are shown here as primary state although it were

excluded from calculation altogether in the year 2006.

•	 Fatalities include all occupants 5 and older, regardless of the restraint use (used, not used, and unknown).

Source: Fatality Analysis Reporting System, 2006 ARF Files, and U. S. Bureau of Census