2 in Iron County (Iron County Heritage Trail) and in Schoolcraft and Mackinac counties (Top of the Lake Scenic Byway), US 41 from Houghton to Copper Harbor (Copper County Trail, also a National Scenic Byway), M-35 (UP Hidden Coast Recreational Heritage Trail), M-123 (Tahquamenon Scenic Heritage Route) and M-134 (M-134 North Huron Byway) Airports There are 43 airports in the Upper Peninsula. Of these, six airports have commercial passenger service: Gogebic-Iron County Airport north of Ironwood, Houghton County Memorial Airport southwest of Calumet, Ford Airport west of Iron Mountain, Sawyer International Airport south of Marquette, Delta County Airport in Escanaba, and Chippewa County International Airport south of Sault Ste. Marie. There are 19 other public use airports with a hard surface runway. These are used for general aviation and charter. Notably, Mackinac Island, Beaver Island, and Drummond Island are all accessible by airports. There are five public access airports with turf runways and thirteen airports for the private use of their owners. There is only one control tower in the Upper Peninsula, at Sawyer. Ferries and bridges The Eastern Upper Peninsula Transportation Authority operates car ferries in its area. These include ferries for Sugar Island, Neebish Island, and Drummond Island. Two ferry companies run passenger ferries from St. Ignace to Mackinac Island. The three major bridges in the Upper Peninsula are: Mackinac Bridge, connecting the Lower Peninsula of Michigan with the Upper; Sault Ste. Marie International Bridge, which connects the city of Sault Ste. Marie to its twin city of Sault Ste. Marie in Canada; and Portage Lift Bridge, which crosses Portage Lake. The Portage Lift Bridge is the world's heaviest and widest double-decked vertical lift bridge. Its center span lifts to provide about of clearance for ships. Since rail traffic was discontinued in the Keweenaw, the lower deck is used to accommodate snowmobile traffic in the winter. As the only land-based link between the north and south sections of the Keweenaw Peninsula, the bridge is crucial to transportation. Railways Lake Superior and Ishpeming Railroad: Transports iron ore over a line from the Empire-Tilden Mine (operated by Cleveland-Cliffs Inc.), south of Ishpeming and Negaunee, to Marquette's port on Lake Superior. Two railroads originally crossed the Upper Peninsula east to west: the Minneapolis, St. Paul and Sault Ste. Marie Railway, informally known as the Soo Line, running west from Sault Ste. Marie roughly along the Lake Michigan shore, and the Duluth,