TABLE 2.
Percentage Change in Fatalities and Injuries in Fatal Crashes on US Roads After Repeal of the National Maximum Speed Law, by Speed Limits: 1990–2005
| No. of States | % Change | P | |
| Rural interstatea | |||
| Fatalities | |||
| Expansion with no change (65 mph) | 10 | −8.43 | .002 |
| Increased 10 mph only after 1995–1996 (65 mph) | 7 | +15.68 | .001 |
| Expansion and 5 mph increase (70 mph) | 18 | +8.25 | .001 |
| Expansion and 10 mph increase (75 mph) | 13 | +13.58 | .001 |
| Injuries | |||
| Expansion with no change (65 mph) | 10 | −3.84 | .027 |
| Increased 10 mph only after 1995–1996 (65 mph) | 7 | +15.25 | .001 |
| Expansion and 5 mph increase (70 mph) | 18 | +17.17 | .001 |
| Expansion and 10 mph increase (75 mph) | 13 | +11.89 | .001 |
| Rural noninterstatea | |||
| Fatalities | |||
| Expansion with no change (65 mph) | 10 | −15.64 | .001 |
| Increased 10 mph only after 1995–1996 (65 mph) | 7 | −0.32 | .889 |
| Expansion and 5 mph increase (70 mph) | 18 | −1.57 | .100 |
| Expansion and 10 mph increase (75 mph) | 13 | +2.35 | .179 |
| Injuries | |||
| Expansion with no change (65 mph) | 10 | −9.17 | .001 |
| Increased 10 mph only after 1995–1996 (65 mph) | 7 | +17.23 | .001 |
| Expansion and 5 mph increase (70 mph) | 18 | +2.65 | .001 |
| Expansion and 10 mph increase (75 mph) | 13 | +3.24 | .006 |
| Urban interstateb | |||
| Fatalities | |||
| 55 mph | 14 | +12.88 | .001 |
| 60–65 mph | 22 | −2.14 | .338 |
| 70–75 mph | 12 | +5.64 | .084 |
| Injuries | |||
| 55 mph | 14 | +10.48 | .001 |
| 60–65 mph | 22 | −3.80 | .038 |
| 70–75 mph | 12 | +18.02 | .001 |
| Urban noninterstateb | |||
| Fatalities | |||
| 55 mph | 14 | −1.07 | .510 |
| 60–65 mph | 22 | −10.45 | .001 |
| 70–75 mph | 12 | +4.26 | .022 |
| Injuries | |||
| 55 mph | 14 | +2.13 | .038 |
| 60–65 mph | 22 | +2.52 | .010 |
| 70–75 mph | 12 | +12.86 | .001 |
Note. Mph = miles per hour. All Poisson mixed-regression models included time trend, intervention, exposure density, and vehicle density as fixed effects and a random intercept for the state effect; models were calculated separately for each speed group. Models included data for fatalities and injuries for 1990 to 2005. Massachusetts, Hawaii, and Washington, DC, were excluded.
Expansion states had previously raised speed limits on limited sections of rural interstate roads from 1987–1988, but after 1995 and the repeal of National Maximum Speed Law, the permissible higher speed limits on rural interstate roads were expanded to include all or most sections of rural interstate roads.
All urban interstate roads had a 55 mph legal speed limit prior to November 1995. Therefore, we stratified urban interstate roads into 3 groups by the legal speed limits after the National Maximum Speed Law was repealed.