Not so long ago in simpler days, the maximum width for all vehicles on all roads in the USA was 8 feet (96 inches.) If a truck was hauling a load wider than that, it required a special permit, and sometimes an escort vehicle. Then a few years ago the federal government passed a law mandating the maximum width for all vehicles on Interstate highways at 8.5 feet (102 inches.) Gradually, states began to "designate" certain other roads as legal for 102-inch vehicles, until today nearly all states permit them on at least some of their four-lane and even two-lane roads. The trucking industry saw this as an opportunity to haul bigger loads in wider trucks. According to Utility, a major truck trailer manufacturer, orders for new 102-inch wide truck trailers now account for over 90% of their business. Buses, even local transit buses and school buses, are now being built on the 102-inch platform.
The federal law only governs Interstate highways, but also mandates that wide vehicles must have "reasonable access" to the Interstate highways. That means that it is legal to exit the Interstate highways, and drive on local roads for a mile or two. In Maryland, it's not to exceed one mile, by the shortest distance possible. In Louisiana, a 102-wide vehicle has "reasonable access, not to exceed ten (10) miles, from designated highways or the Interstate System, to be allowed to facilities for food, fuel, repairs, and rest, unless otherwise prohibited.