Crash rates with drivers, driver-kilometres and driver-days as denominator were compared, using survey estimates and the annual frequency of crashes in Ontario. Rates by age, sex and region for all crashes and injury or fatal crashes were computed. Young men remained at high risk for all types of denominator;​ older women had high rates when driver-km was the denominator. For driver-days, the older men and women drivers had very similar rates, suggesting that the apparent excess among older women is due to differences in speed and environment. Such differences also appear in the comparisons of rural residents with urban and northern residents. Exposure time is better able to explain crash risk among drivers and regions with very different driving patterns and environments.