Final answer:
According to FMCSA regulations, commercial motor vehicle carriers are required to retain accident reports for a minimum of three years following the date of the accident.
Step-by-step explanation:
The length of time accident reports must be kept can vary depending on the regulations set by the overseeing authority. For commercial motor vehicle carriers operating in the United States, the Federal Motor Carrier Safety Administration (FMCSA) requires that the carrier retain accident reports for a significant period. According to FMCSA regulations, accident reports must be kept by the carrier for a minimum of three years following the date of the accident. This time frame ensures that there is sufficient historical data for reference in case of audits, legal actions, or for analytical purposes to prevent future accidents.