1. In 1917, Michigan's Mackinac Bridge Authority was established to oversee the construction of the Mackinac Bridge, which would become the longest suspension bridge in the world at the time of its completion in 1957.

2. On October 15, 1966, the University of Michigan's football team, led by legendary coach Bo Schembechler, defeated Michigan State University's team in what has become known as the "Game of the Century." The Wolverines won the game 17-10 and went on to win the Big Ten Conference championship that year.

3. The Great Lakes Shipwreck Historical Society was founded on October 15, 1978, in Sault Ste. Marie, Michigan. The society is dedicated to preserving the history and artifacts of Great Lakes shipwrecks and conducting underwater research to better understand these tragedies.

4. October 15, 2012, marked the first day of legal same-sex marriages in Michigan. However, these marriages were briefly halted by the state's attorney general, leading to a years-long legal battle that eventually resulted in the U.S. Supreme Court legalizing same-sex marriage nationwide in 2015.

5. On October 15, 2020, Governor Gretchen Whitmer announced that Michigan would aim to become carbon-neutral by 2050, joining a growing number of states and countries committed to combating the effects of climate change. The plan includes investments in renewable energy, energy efficiency, and electric vehicle infrastructure.