The Detroit River flows for 24 nautical miles (44 km; 28 mi) from Lake St. Clair to Lake Erie as a strait in the Great Lakes system and forms part of the border between Canada and the United States. The river divides the metropolitan areas of Detroit, Michigan and Windsor, Ontario - an area referred to as Detroit–Windsor. The two cities are connected by the Ambassador Bridge, the Detroit–Windsor Tunnel and the Michigan Central Railway Tunnel.

The river's name comes from the French Rivière Détroit, meaning River of the Strait. The Detroit River has served an important role in the history of Detroit and is one of the busiest waterways in the world. The river travels west and south from Lake St. Clair to Lake Erie, and the whole river is coterminous with the border between Canada and the United States.

The river serves as an important transportation route connecting Lake Michigan, Huron, and Superior to the St. Lawrence Seaway and Erie Canal. When Detroit underwent rapid industrialization at the turn of the 20th century, the Detroit River became notoriously polluted and toxic. In recent years, however, the ecological importance of the river has warranted a vast restoration effort, and the river today has a wide variety of economical and recreational uses. There are numerous islands in the Detroit River, and much of the lower portion of the river is incorporated into the Detroit River International Wildlife Refuge. The portion of the river in the city of Detroit has been organized into the Detroit International Riverfront and the William G. Milliken State Park and Harbor. The Detroit River is designated an American Heritage River and a Canadian Heritage River — the only river to have this dual designation.

The Detroit River was first navigated by non-natives in the 17th century. The Iroquois traded furs with the Dutch colonists at New Amsterdam by traveling through the Detroit River. The French later claimed the area for New France. The famed sailing ship Le Griffon reached the mouth of the Detroit River in mid-August 1679 on its maiden voyage through the Great Lakes. Later, when the French began settling in the area, they navigated the river using canoes made of birch or elm bark.

French explorer Antoine Laumet de La Mothe, sieur de Cadillac sailed up the Detroit River on July 23, 1701. The next day, he established Fort Pontchartrain du Détroit, which became Detroit. The river itself became known as the Rivière Détroit, in which détroit is French for "strait". The river was known literally as the "River of the Strait".

The Detroit River — and the larger area surrounding it — was taken from the French by Great Britain during the French and Indian War. It was claimed by the newly formed United States during the American Revolution but was not turned over by the British until 1796. During the War of 1812, the Detroit River served as a major barrier between the American Michigan Territory and British Upper Canada, especially during the Battle of Fort Detroit in August 1812, when Detroit briefly fell to the British. Following the completion of the Erie Canal in 1817, which opened up easier travel to Lake Erie from the East Coast of the United States, the Detroit River became a heavily traversed route for settlers traveling to northern Michigan, and Detroit, as well, experienced a sudden increase in population. Following the Patriot War which nearly saw a battle between British regulars and Michigan militia on the ice-covered Detroit River, Fort Wayne was constructed at Detroit to counter Britain's riverside Fort Malden at Amherstburg.

During the American Civil War (1861–1865), the Union feared that the seceded Confederate States of America (CSA) would plan a northerly attack from Canada, which was still owned by the British Empire and remained neutral in the war. The Union feared that the CSA would cross the Detroit River to launch this attack. For that reason, the Detroit River was heavily patrolled and the fortification at Fort Wayne improved, even though it was far removed from any real combat. While no major attack came from Canada, a plot to capture the U.S. Navy warship, USS Michigan and liberate Confederate prisoners from Johnson Island, in western Lake Erie, was narrowly averted only after the Confederates had captured two passenger steamships.

At the beginning of the 20th century, Detroit's industrialization took off on an unprecedented scale. The Detroit River became the busiest commercial river in the world and was dubbed "the Greatest Commercial Artery on Earth" by The Detroit News in 1908. In 1907, the Detroit River carried 67,292,504 tons (61 billion kg) of shipping commerce through Detroit to locations all over the world. For comparison, London shipped 18,727,230 tons (16 billion kg), and New York shipped 20,390,953 tons (18 billion kg).

en.wikipedia.org/wiki/Detroit_River