What) The Mackinac Bridge is a suspension bridge spanning the Straits of Mackinac to connect the non-contiguous Upper and Lower peninsulas of the U.S. state of Michigan. Opened in 1957, the bridge (familiarly known as "Big Mac" and "Mighty Mac") is the third longest in total suspension in the world.

    Construction cost: $99.8 million. Height of the roadway at mid-span: 200 feet above water level. Height of towers above water: 552 feet. Painting of the bridge takes seven years, and when painting is complete, it begins again. The bridge celebrated its 150 millionth vehicle crossing in 2009. Current toll is $3.50 (1)

    Where) If you miss then it you have to swim.

    Why) Crossing the bridge seems to be the best way to get the information required to decide whether Lake Michigan and Lake Huron are one lake or two.

Here we are at the start of the bridge.  As you can see, there appears to be a lot of water on both sides.

Yes, if you zoom in to the railing close enough it appears to be all water.

Anyway, this is the best artistic photo I could take.  As usual it is nowhere near as good as ...

... this one. I am not sure which side this is but when you look at it from this view it certainly appears to be one lake. (2)

Pam and I both agreed that there are only four Great Lakes. Was that your answer when you looked at the satellite photo? (3)