Question: The Straits of Mackinac Shipwreck Preserve are divided in two by a bridge spanning how long?

Context articles: USCGC Biscayne Bay (WTGB-104)
SS Eber Ward
Straits State Park
Ferries in Michigan
Mackinac Bridge
Mackinac Bridge Authority
Mackinaw City, Michigan
Cut River Bridge
Straits of Mackinac Shipwreck Preserve
Straits of Mackinac

 is a United States Coast Guard Cutter and an icebreaking tug.
 She is based at Coast Guard Station St. Ignace with a primary area of operation in the Straits of Mackinac including Mackinac Island, Mackinac Bridge, and the northern portions of Lakes Michigan and Huron and occasionally Lakes Superior, Erie and their connecting rivers.
 Beyond her role as an icebreaker, "Biscayne Bay" performs search and rescue and law enforcement functions.
SS "Eber Ward" was a package freighter that served ports on the Upper Great Lakes from her launching in 1888 until she sank in the Straits of Mackinac on April 20, 1909, with the loss of five lives.
 The sunken cargo ship is a feature of the present-day Straits of Mackinac Shipwreck Preserve.
Straits State Park is a state park in the U.S. state of Michigan located in St. Ignace, Mackinac County, on the northern shore of the Straits of Mackinac.
 The Father Marquette National Memorial and park is also located within the state park boundaries.
 The park is equipped with 255 campsites and offers several ideal locations for viewing the Mackinac Bridge.
Due to its unique geography, being made of two peninsulas surrounded by the Great Lakes, Michigan has depended on many ferries for connections to transport people, vehicles and trade.
 The most famous modern ferries are those which carry people and goods across the Straits of Mackinac to the car-free Mackinac Island but before the Mackinac Bridge was built, large numbers of ferries carried people and cars between the two peninsulas.
 Other ferries continue to provide transportation to small islands and across the Detroit River to Canada.
 Ferries once provided transport to island parks for city dwellers.
 The state's only national park, Isle Royale cannot be reached by road and is normally accessed by ferry.
 The largest ferries in Michigan are the car ferries which cross Lake Michigan to Wisconsin.
 One of these, the SS "Badger" is one of the last remaining coal steamers on the Great Lakes and serves as a section of US Highway 10 (US 10).
 The "Badger" is also the largest ferry in Michigan, capable of carrying 600 passengers and 180 autos.
The Mackinac Bridge ( ) is a suspension bridge spanning the Straits of Mackinac to connect the Upper and Lower Peninsulas of the U.S. state of Michigan.
 Opened in 1957, the 26372 ft bridge (familiarly known as "Big Mac" and "Mighty Mac") is the world's 19th-longest main span and the longest suspension bridge between anchorages in the Western Hemisphere.
 The Mackinac Bridge is part of Interstate 75 and the Lakes Michigan and Huron components of the Great Lakes Circle Tours across the straits; it is also a segment of the U.S. North Country National Scenic Trail.
 The bridge connects the city of St. Ignace on the north end with the village of Mackinaw City on the south.
The Mackinac Bridge Authority is an independent state agency of the U.S. state of Michigan that operates the Mackinac Bridge across the Straits of Mackinac.
 The Mackinac Bridge Authority has been directed by the state of Michigan to maintain the Mackinac Bridge as a self-supporting facility.
 The Mackinac Bridge is a toll bridge, with the tolls set at a level determined by the authority and its governing board.
Mackinaw City is a village in Emmet and Cheboygan counties in the U.S. state of Michigan.
 The population was 806 at the 2010 census; the population surges during the summer tourist season, including an influx of tourists and seasonal workers who serve in the shops, hotels and other recreational facilities there and in the surrounding region.
 Mackinaw City is at the northern tip (headland) of the Michigan's Lower Peninsula along the southern shore of the Straits of Mackinac.
 Across the straits lies the state's Upper Peninsula.
 These two land masses are physically connected by the Mackinac Bridge, which runs from Mackinaw City north to St. Ignace.
 Mackinaw City is also the primary base for ferry service to Mackinac Island, located to the northeast in the straits.
Cut River Bridge is a cantilevered steel deck bridge over the Cut River in the Upper Peninsula of the U.S. state of Michigan.
 It is located along U.S. Highway 2 (US 2) in Hendricks Township, Mackinac County, between Epoufette and Brevort, about 25 mi northwest of St. Ignace and the Straits of Mackinac.
 There is a long but not often traversed wooden staircase to the valley below that was constructed some time after the construction of the bridge itself.
The Straits of Mackinac Shipwreck Preserve is a 148 sqmi state preserve in and around the Straits of Mackinac.
 The preserve is divided in two by the Mackinac Bridge.
 The waters of the preserve include the waters offshore from Mackinaw City and St. Ignace, as well as all or part of the shorelines of Bois Blanc Island, Mackinac Island, Round Island, and St. Helena Island.
The Straits of Mackinac ( ) is a series of narrow waterways in the U.S. state of Michigan, between Michigan's Lower and Upper Peninsulas.
 The main strait flows under the Mackinac Bridge and connects two of the Great Lakes, Lake Michigan and Lake Huron.
 The main strait is 5 mi wide and 20 fathom deep.
 Hydrologically, the two connected lakes can be considered one, which is called Lake Michigan–Huron.
 Historically, the region around the Straits was known by the native Odawa people as Michilimackinac.
 The Straits of Mackinac is "whipsawed by currents unlike anywhere else in the Great Lakes."