I really do not know Maryland law. They may allow 102 wide trailers off the National Highway System. Like I said state law applies.
On the Nat Hwy system states have no control. They must allow doubles; 102 wide; and 53 ft long. That is federal law. It was passed years ago.
The federal government was pushed by some real big companies (LTL) that made mega contributions to the right people to get doubles nationwide. Some states complained so access was limited to what we know today as the Nat Hwy System. At the same time they increased single trailer size to 53 ft by 102 wide. Access was also allowed 3 miles from the system to reach terminals.
That is the federal law and it still stands today.
Over the years everyone has slowly gone to 102 wide. Boats; RV's; and just about every semi trailer on the road. As these became more popular the 3 mile access limit was stretched just from use and non enforcement.
Ga use to have signs on every exit off the interstate at the 3 mile point but I do not know if they still do.
Follow the link to maps of the Nat Hwy System.