Lake Michigan is one of the five Great Lakes of North America, and the only one located entirely within the United States. It is bounded, from west to east, by the U.S. states of Wisconsin, Illinois, Indiana, and Michigan. The word "Michigan" was originally used to refer to the lake itself, and is believed to come from the Ojibwa Indian word mishigami, meaning "great water." The lake is slightly larger than the country of Croatia.

Lake Michigan is the only one of the Great Lakes wholly within the borders of the United States; the others are shared with Canada. It has a surface area of 22,400 square miles (58,016 km²), making it the largest lake entirely within one country by surface area (Lake Baikal, in Russia, is larger by water volume), and the fifth largest lake in the world. It is 307 miles (494 km) long by 118 miles (190 km) wide with a shoreline 1,640 miles (2,633 km) long. The lake's average depth is 279 feet (85 m), while its greatest depth is 923 feet (281 m). It contains a volume of 1,180 cubic miles (4,918 km³) of water. Its surface averages 577 feet (176 m) above sea level, the same as Lake Huron, to which it is connected through the Straits of Mackinac. - Wikipedia

Lake Michigan, the second largest Great Lake by volume with just under 1,180 cubic miles of water, is the only Great Lake entirely within the United States. Approximately 118 miles wide and 307 miles long, Lake Michigan has more than 1,600 miles of shoreline. Averaging 279 feet in depth, the lake reaches 925 feet at its deepest point. The lake's northern tier is in the colder, less developed upper Great Lakes region, while its more temperate southern basin contains the Milwaukee and Chicago metropolitan areas. The drainage basin, approximately twice as large as the 22,300 square miles of surface water, includes portions of Illinois, Indiana, Michigan and Wisconsin. Lake Michigan is hydrologically inseparable from Lake Huron, joined by the wide Straits of Mackinac. - Great Lakes Information Network

The northern part is in the colder, less developed upper Great Lakes region. It is sparsely populated, except for the Fox River Valley, which drains into Green Bay. This bay has one of the most productive Great Lakes fisheries but receives the wastes from the world's largest concentration of pulp and paper mills. The more temperate southern basin of Lake Michigan is among the most urbanized areas in the Great Lakes system. It contains the Milwaukee and Chicago metropolitan areas. This region is home to about 8 million people or about one-fifth of the total population of the Great Lakes basin. - EPA

About 10,000 to 14,000 years ago, at the end of the Great Ice Age, ancient peoples traveled over extinct land bridges to the Great Lakes region. These Woodland Indians depended on the vast forests of the region for their survival and engaged in various forms of agriculture. European settlers were also drawn to the shores of Lake Michigan because of its natural resources. Today Lake Michigan is home to the nation’s third-largest population center and provides drinking water for over 10 million people. - Wisconsin DNR

The British took control of the Straits of Mackinac after the French and Indian War and Major Patrick Sinclair chose the bluffs of the island for Fort Mackinac in 1780.

Although the British built Fort Mackinac to protect their settlement from attack by Americans and native tribes, the fort was never attacked during the American Revolutionary War and the entire Straits area was officially acquired by the United States through the Treaty of Paris in 1783. However, much of the British forces did not leave the Great Lakes area until after Jay's Treaty established U.S. sovereignty over the entire Northwest Territory in 1794. During the War of 1812, the British captured the fort in the first battle of the conflict because the Americans had not yet heard that war had been declared. The victorious British attempted to protect their prize by building Fort George on the high ground behind Fort Mackinac. In 1814, the Americans and British fought a second battle on the north side of the island. The American second-in-command, Major Andrew Hunter Holmes, was killed and the Americans failed to recapture the island.

Despite this outcome, the Treaty of Ghent forced the British to return the island and surrounding mainland to the U.S. in 1815. The United States reoccupied Fort Mackinac, and renamed Fort George Fort Holmes, after Major Holmes. The fort even served as a prison for three Confederate sympathizers.

Following the Civil War, the island became a popular tourist destination for residents of cities on the Great Lakes. Much of the federal land on Mackinac Island was designated as Mackinac National Park in 1875, just three years after Yellowstone was designated as the first national park. - Wikipedia

Green Bay is an arm of Lake Michigan, located along the south-west coast of Michigan's Upper Peninsula and the east coast of Wisconsin. It is separated from the rest of the lake by the Door Peninsula in Wisconsin, the Garden Peninsula in Michigan, and the chain of islands between them, all formed by the Niagara Escarpment. Green Bay is some 120 miles (193 km) long, with a width ranging from about 10 miles (16 km) to 20 mi (32 km). It is 186 square miles (480 km²) in area.

At the southern end of the bay is the city of Green Bay, Wisconsin, where the Fox River enters the bay. The Leo Frigo Memorial Bridge (formerly known as the Tower Drive bridge) spans the point where the bay ends and the Fox River begins. Locally, the bay is often called the Bay of Green Bay to distinguish the bay from the city. The bay is navigable by large ships. - Wikipedia