Every outbound (or "headhaul") movement leaves the truck somewhere it did not start. A backhaul turns the return into revenue rather than deadhead. Because the carrier is going to make the trip regardless, a backhaul can be priced lower than the headhaul and still improve the economics of the round trip.
Backhaul availability is a property of the lane, not the load. Some corridors are balanced — roughly equal freight in both directions — and some are heavily one-directional, which is why rates out of produce regions or import ports differ so much by season and direction.
Carriers that run dedicated or repeating lanes often line up a standing backhaul with a broker or shipper so the return is covered before the truck leaves. Spot-market carriers rebook the return from a load board while the outbound is still in transit.
Example
A carrier hauls appliances from Louisville to Atlanta for $1.90 per mile. Rather than deadhead 420 miles back, the dispatcher books a backhaul of building materials from Atlanta to Nashville at $1.35 per mile, then a short repositioning move home. The lower backhaul rate still adds roughly $560 of revenue to a trip that would otherwise have run empty.
Why it matters
Consistent backhaul coverage is often the difference between a lane a carrier can run profitably every week and one it takes only when the headhaul rate is unusually high.