A “trailer” to most of us means something that’s part of a heavy combination vehicle, including the ubiquitous 18-wheeler. They are usually what I write about here.

But of course, there are also light- and medium-duty trailers used by tradesmen, consumers and enthusiasts. They have to get from factories where they’re built to dealers and customers; sometimes they’re hauled on flatbeds or lowboys, but they’re also towed by specialized haulers using heavy pickups.

Like big rigs, those vehicle combinations are subject to state length restrictions, or were, until recent passage of the federal FAST (Fixing America’s Surface Transportation) Act.

Many state laws restricted towing of light- and medium-duty trailers to a single unit, according to the National Association of Trailer Manufacturers. Eight states allowed a truck to tow two trailers, but allowable lengths varied and none of the eight were contiguous.

“Often drivers would be able to tow two trailers through one state, but then have to drop a trailer to get it to a dealer in a state that didn’t allow tandem deliveries,” said Pam O’Toole Truesdale, the association’s executive director. “They would then have to go back and pick up the trailer, so that they delivered one at a time in that specific state.”

The inefficiencies were frustrating to NATM members, so they and association staffers worked for years to educate members of Congress about it. They got Congress to include a provision in the FAST Act that legalized tandem towing in all states, and liberalized combination length.

“This legislation allows tandem delivery up to 82 feet on interstate highways and includes ‘reasonable access’ to interstate highways,” she said. “This law supersedes state length limitations.”

That sounds familiar to folks who lived through changes brought by the federal Surface Transportation Assistance Act of 1982. It dictated "reasonable access" to interstates for longer semitrailers and twin 28-foot pups throughout the United States, including states that had outlawed them.

Drivers pulling such combinations need CDLs, and they're usually owner-operators. New light- and medium-duty trailers are transported empty, so while they can be large, they’re not very heavy. And most have brakes, so stopping power should be more than sufficient.