>To reach muskrat county, you head east on Route 50 to Cambridge, then turn southwest, passing the Harriet Tubman Underground Railroad State Park and winding through the marshes of the Blackwater National Wildlife Refuge. It’s here, beneath the scrubby pines and amid tall, dun-colored grasses that muskrats, a species native to wetlands throughout the continental United States, make their homes. The marshlands are full of what locals describe as “boot-sucking mud” and act as a natural filter, cleaning the water before it reaches the nearby Chesapeake Bay.