From
https://www.dol.gov/whd/regs/compliance/whdfs22.pdf
Travel Time: The principles which apply in determining whether time spent in travel is compensable time depends upon the kind of travel involved.
Home to Work Travel: An employee who travels from home before the regular workday and returns to his/her home at the end of the workday is engaged in ordinary home to work travel, which is not work time.
Home to Work on a Special One Day Assignment in Another City: An employee who regularly works at a fixed location in one city is given a special one day assignment in another city and returns home the same day. The time spent in traveling to and returning from the other city is work time, except that the employer may deduct/not count that time the employee would normally spend commuting to the regular work site.
Travel That is All in a Day's Work: Time spent by an employee in travel as part of their principal activity, such as travel from job site to job site during the workday, is work time and must be counted as hours worked.
Travel Away from Home Community: Travel that keeps an employee away from home overnight is travel away from home. Travel away from home is clearly work time when it cuts across the employee's workday. The time is not only hours worked on regular working days during normal working hours but also during corresponding hours on nonworking days.
As an enforcement policy the Division will not consider as work time that time spent in travel away from home outside of regular working hours as a passenger on an airplane, train, boat, bus, or automobile.