The Straits of Mackinac are narrow waterways that connect the Upper and Lower Peninsulas of the U.S. state of Michigan. The Mackinac Bridge crosses the straits. The main strait is 3.5 miles (5.6 kilometers) wide and has a maximum depth of 295 feet (90 meters). It connects Lake Michigan and Lake Huron, which are studied together as one large body of water called Lake Michigan–Huron. The Native American Odawa people called the area around the straits "Michilimackinac."

Three islands form the eastern edge of the straits. Bois Blanc Island and Mackinac Island are inhabited, while Round Island is not inhabited and is a protected wilderness area. The straits are important shipping routes that move raw materials and finished goods, such as iron from Minnesota to steel mills in Gary, Indiana. Before railroads connected Chicago to the east, many immigrants traveled to the Midwest and Great Plains by ship on the Great Lakes. The straits are 5 miles (8 kilometers) wide at their narrowest point, where the Mackinac Bridge spans them. Before the bridge was built, car ferries transported vehicles across the straits. Today, passenger-only ferries carry people to Mackinac Island, which does not allow cars. Visitors can take vehicles on a car ferry to Bois Blanc Island.

The straits are shallow and narrow enough to freeze in winter. Icebreakers help ships travel through the straits year-round. The straits were important routes for Native American tribes and fur trading. The name "Mackinac" comes from Mackinac Island. The Ojibwe people called the island "Mitchimakinak," meaning "Big Turtle." When the British explored the area, they shortened the name to "Mackinac."

Mackinaw City, on the southern side of the straits, is home to Fort Michilimackinac, a reconstructed French fort built in 1715. St. Ignace, on the northern side, is where a French Catholic mission to Native Americans was founded in 1671. Fort Mackinac, on Mackinac Island, was a British and early American military base and fur trade center built in 1781.

History

A French Catholic mission for Native Americans was established in St. Ignace in 1671. In 1715, the French built Fort Michilimackinac on the southern end of the narrow straits. In 1781, the British replaced this fort with Fort Mackinac, located on Mackinac Island.

Enbridge Line 5 was constructed in 1953 as an extension of the 1,150-mile (1,850 km) Interprovincial Pipe Line Company route, which runs west of the famous Mackinac Bridge. This pipeline transports oil from Alberta to Lake Superior. On December 12, 2018, Michigan Governor Rick Snyder signed a law to create the Mackinac Straits Corridor Authority and selected its first members.

Today

The straits are watched over by a group of United States Coast Guard members stationed at Graham Point, St. Ignace. A path for ships through the winter ice is kept open by the Coast Guard's Great Lakes icebreaker ship, USCGC Mackinaw, which is based in Cheboygan, near the eastern side of the straits. This ship began its work during the 2005/06 ice season.

Two ferry companies operate from Mackinaw City and St. Ignace, helping move tourists and people who live there to Mackinac Island. The companies are Shepler's Ferry and the Arnold Transit Company.

Most of the straits have been designated by the state of Michigan as the Straits of Mackinac Shipwreck Preserve. This protected area along the water's edge honors the people who died on boats and ships that sank in these dangerous shipping lanes.

Lighthouses in the Straits of Mackinac include:

• The McGulpin Point Light, located on McGulpin Point, three miles (5 km) west of Fort Michilimackinac.
• The Old Mackinac Point Light, in Mackinaw City, which is open to the public.
• The Round Island Light, on Round Island, which is not open to visitors but can be seen from the Mackinac Island ferry route.

Enbridge pipeline

West of the famous Mackinac Bridge is Enbridge's pipeline, known as Enbridge Line 5. It was built in 1953 as an extension of the 1,150-mile (1,850 km) Interprovincial Pipe Line Company route, which carries oil from Alberta to Lake Superior. The 1953 pipeline enters the water of the Straits of Mackinac on the north shore at St. Ignace, Michigan, and runs along the bottom of the Straits, which is nearly 250 feet (76 m) deep in some areas. By 2013, Enbridge had increased the maximum daily capacity of the pipeline to 540,000 barrels (86,000 cubic meters). When promoting the pipeline to residents near the Straits, the developers said it was "essential to the defense of the United States and the whole North American continent." A study by the University of Michigan examined the risks of a pipeline leak, leading experts and local governments to call for the pipeline to be shut down.

In late June 2019, the state of Michigan filed a lawsuit asking the Ingham County Court to order the removal of the part of Line 5 that runs under the Straits of Mackinac. A Reuters news report described Line 5 as "a critical part of Enbridge’s Mainline network, which delivers most Canadian crude exports to the United States." The lawsuit claims the pipeline is a public nuisance and violates the Michigan Environmental Protection Act because it could cause pollution. The report also notes that it is unclear whether Line 5 could operate without the section that runs under the Straits.

Mackinac Straits Corridor Authority

On December 12, 2018, Michigan Governor Rick Snyder signed a law to create the Mackinac Straits Corridor Authority. This group is responsible for managing the building and operation of a tunnel to hold a new Enbridge Line 5 under the lake bed in the Mackinac Straits. Governor Snyder also named the first members of the authority: Geno Alessandrini from Iron Mountain, Anthony England from Ypsilanti, and Michael Zimmer from Dimondale. These members serve six-year terms.