Complex sentence: The U.S. Army widened the Natchez Trace (which connected the region to Nashville, Tennessee), in order to accommodate wagons and placed it under the care of the Postmaster General of the United States, making it one of the earliest national highways.
Split into simpler sentences: The U.S. Army widened the Natchez Trace (which connected the region to Nashville, Tennessee), in order to accommodate wagons. It was placed under the care of the Postmaster General of the United States, making it one of the earliest national highways.