A couple of trivia bits about Michigan. One, Michigan has the longest freshwater coastline of any state in the union (and the longest coastline of the lower 48). Two, with over 100 lighthouses, Michigan has more lighthouses than any state in the union. So far I've managed to visit 40 of them. I think the only ones that I haven't visited in the lower peninsula are the ones on accessible by boat. I still have a trove of them to visit in the Upper Peninsula though.
Because Michigan borders four of the five Great Lakes and the Great Lakes have been used for shipping for a long time, Michigan has a pretty rich nautical heritage. Despite all appearances, the Great Lakes are pretty dangerous and because of that, there are a pretty significant number of lighthouses.
A lighthouse is typically used to indicate an area that is dangerous to ships. They are also used as guides into ports. The earliest lighthouses were typically a fire pit on top of a hill and were used to guide the entrances into ports. One of the earliest lighthouse towers was the lighthouse at Alexandria which was built around 300 BC. It was approximately 400 feet tall and was the tallest man-made structure for a long time. It became damaged by earthquakes between 956 and 1323 AD and became an abandoned ruin.
Modern lighthouses didn't come into existence until the early 18th Century as long distance sea travel became more prevalent. As navigational tools became more accurate, their use fell into decline although many of them are still used as aids to navigation (but not as much as they used to be).
For these posts, I'm going to start at the southeast end of the state and work my way around. As I said, I haven't been to all of the Michigan lighthouses but these are a pretty good number of them. I'm not going to provide a ton of detail on this post except maybe how to get to them.