There are more than twenty (20) exemptions from overtime enumerated in the Fair Labor Standards Act.  Mostly, employers only are concerned with the three so-called white-collar exemptions (executive, administrative, professional).  There is, however, an exemption for truck drivers, bus drivers and other individuals who drive for a living and who cross state lines.  This is called the Motor Carrier Exemption and there must be an element of interstate commerce involved.

Interstate commerce is easy to understand if a driver crosses state lines.  But, what if the driver does not cross state lines and drives entirely within one state.  That movement can still be considered interstate commerce under the doctrine known as "practical continuity."  If there is such a practical continuity of movement for the shipment, such that the intent of the shipper was to have that shipment pass through interstate commerce, in a single, unified trip, then the interstate nature of the trip also continued.  The otherwise intrastate driving truckers would nevertheless be exempt from overtime under the Motor Carrier exemption.  Thus, the drivers working for an intrastate beer distributor were found to be exempt from overtime because the beer they drove, which had been imported from out-of-state, was originally destined for the in-state customers by the shipper in the distant state.

Further, concerning bus drivers,  if an passenger can buy a ticket which is good for both an intrastate trip and then an interstate trip, this is known as "through-ticketing" and also is considered part of the continuous stream of interstate commerce.  Similarly, where a Colorado ski resort contracted with a limousine service to provide transportation from the Denver airport to the ski resort, those drivers were found to be in interstate commerce because they completed the last leg of the interstate trip  It should be highlighted that the amount of interstate traffic to qualify for the exemption is rather minimal. 

For employers of drivers, this exemption must be considered.  It could save thousands of dollars in overtime costs.