In California between 1998-2007, 21% of drivers 16 and older in fatal crashes had an invalid license. California is much worse than the national average of 14%. See the attached document (Traffic Safety Facts NHTSA DOT HS 811 229 "Trends in Fatal Crashes Among Drivers With Invalid Licenses")
Gebers and Peck (1987) examined crash records of the general driver population and drivers who would soon become disqualified. They reported that probabilities of traffic convictions (DUI and other infractions) and crashes were 4- 20 times higher for the latter than the former, depending on the types of convictions and crashes. For example, hit-and-run crash involvement probability was nearly 20 times higher for disqualified drivers (relative to the general population); DUI crash involvement probability was nearly 6 times higher, and DUI conviction rate was almost 4 times higher.
In California it was found that, compared with validly licensed drivers, S/R drivers are over involved in fatal crashes by a factor of 3.7_1, while unlicensed drivers are even more over represented, by a factor of 4.9:1 (DeYoung et al., 1997)
DMV estimates there are approx 1.3 million Californians with a suspended/revoked driver's license.
"Overall, studies thus far of drivers whose licenses have been suspended or revoked or who are unlicensed have been linked to recidivism of drivers suspended for driving under the influence of alcohol." Unlicensed to Kill, the Sequel - AAA Foundation for Traffic Safety
Invalid Licenses of Drivers in FARS_811229