Spanning the two Michigan peninsulas is the Mackinac Bridge, the longest suspension bridge in the western hemisphere . It is always a highlight of our trips to the Upper Peninsula. When you say “Big Mac” to a Michigander, the bridge is what they think of, not the hamburger.

Counting the approaches, the bridge is five miles long.

What makes it so interesting is the very nature of its construction. A suspension bridge is designed to move to accommodate wind.

And high above the Straits of Mackinac, where Lake Michigan merges with Lake Huron at the very tip of the Michigan mitt, there is always wind.


The view from Mackinaw City of the Mackinac Bridge. And yes, the two names are spelled differently. Pronounced exactly the same but spelled differently. I have no idea why.

In fact, according to the Mackinac Bridge Authority, the state agency that runs the bridge, it is possible that the deck at center span could move as much as 35 feet (east or west) due to high winds.


This would only happen under severe wind conditions, mind you. And the deck would not swing or “sway” but rather move slowly in one direction based on the force and direction of the wind. After the wind subsides, the weight of the vehicles crossing would slowly move it back into center position.

Sometimes, the bridge is shut down. Electronic signs along I-75 so alert drivers and a low power radio station continuously broadcasts bridge conditions. Large trucks usually require an escort.

But RVs usually have no problems.

I say usually. I’ve crossed the bridge in our Roadtrek a dozen times. On a couple of occasions, I was aware of some pretty stiff cross winds. Nothing that caused any serious apprehension, but enough to keep my speed down.

Occasionally, there have been vehicles rolled over on the bridge because of high winds.

In 1989 a woman driving a two-year-old Yugo inexplicably stopped her super light weight vehicle on the bridge over the open steel grating on the bridge’s span. A gust of wind through the grating blew her vehicle off the bridge.

That’s the only death not attributed to accidents or suicides. The most recent suicide was late last year, by someone who jumped over the rail. In 1997  a man in a Ford Bronco intentionally drove off.

But such incidents are very rare.

Yet, because of the nature of suspension bridges, there’s always an element of adventure in crossing the Big Mac.

The view is always spectacular.

I put together this little video during our most recent crossing. It was late on a cloudy day on mid-September.

Some 200 feet below it, ferry boats could be seen making their way back and forth to nearby Mackinac Island from Mackinaw City, the last town in the Lower Peninsula and St. Ignace, the first town in the UP.

Before the bridge was opened in 1957, automobile ferries made the crossing.

Every Labor Day, people can walk across the bridge. I’ve participated in a couple of bicycle rides that also cross the bridge as well. But the bridge is only open for vehicular traffic except on a very few special occasions during the year.

So driving is how most of us cross. If you haven’t driven across the Big Mac bridge, put it on your bucket list.

If you want to spend the night and check out the bridge, the best place to do so is on the UP side, at Straits State Park in St. Ignace. There are spots right along the lake shore with a view like this:


From Straits State Park in St. Ignace, looking south. This was from our campsite there.

If you just want to get close and take some photos or maybe have a picnic, the Fort Michilimackinac State Park on the Mackinaw City side has lots of  RV parking with great bridge views like these:


Sunset, looking west from Fort Michilimackinac State Park in Mackinaw City


You can walk right under the bridge at Fort Michilimackinac State Park in Mackinaw City


Counting the approaches, the Mackinac Bridge is five miles long. This is from Fort Michilimackinac State Park in Mackinaw City


Meanwhile, here’s some facts and figures on the bridge:

Total Length of Bridge (5 Miles) 26,372 Ft. 8,038 Meters
Total Length of Steel Superstructure 19,243 Ft. 5,865 Meters
Length of Suspension Bridge (including Anchorages) 8,614 Ft. 2,626 Meters
Total Length of North Approach 7,129 Ft. 2,173 Meters
Length of Main Span (between Main Towers) 3,800 Ft. 1,158 Meters



Height of Main Towers above Water 552 Ft 168.25 Meters
Maximum Depth to Rock at Midspan Unknown Unknown
Maximum Depth of Water at Midspan 295 Ft. 90 Meters
Maximum Depth of Tower Piers below Water 210 Ft. 64 Meters
Height of Roadway above Water at Midspan 199 Ft. 61 Meters
Underclearance at Midspan for Ships 155 Ft. 47 Meters
Maximum Depth of Water at Piers 142 Ft. 43 Meters
Maximum Depth of Piers Sunk through Overburden 105 Ft. 32 Meters




Total Length of Wire in Main Cables 42,000 Miles 67,592 km
Maximum Tension in Each Cable 16,000 Tons 14,515,995 kg
Number of Wires in Each Cable 12,580
Weight of Cables 11,840 Tons 10,741,067 kg
Diameter of Main Cables 24 1/2 Inches 62.23 cm
Diameter of Each Wire 0.196 Inches .498 cm