How Long Is the Suspension Part of the Mackinac Bridge?

The Mackinac Bridge, often called the "Mighty Mac," is a stunning suspension bridge connecting Michigan's Upper and Lower Peninsulas. One of the most common questions asked by travelers and bridge enthusiasts is, "How long is the suspension part of the Mackinac Bridge?" The answer is straightforward: the main suspension span measures 3,800 feet (1,158 meters). However, the full suspension structure includes additional components. This article explains the exact dimensions, compares it to other famous bridges, and provides practical tips for those planning to cross it.

The Main Suspension Span: 3,800 Feet

The center span of the Mackinac Bridge—the suspended section between the two main towers—is exactly 3,800 feet long. This was the longest suspension span in the world when the bridge opened in 1957, and it remains one of the longest in the United States today. The towers rise 552 feet above the water, and the main cables supporting the span are 24½ inches in diameter, composed of over 12,000 individual wires.

Total Suspension Structure

While the main span is the most visible part, the entire suspension system includes the two side spans that extend from the towers to the anchorages on each shore. The total length of the suspended roadway (main span plus side spans) is about 7,400 feet (1.4 miles). The anchorages are massive concrete blocks that hold the cables in place. Combined, the suspension bridge portion accounts for the majority of the total bridge length of 26,372 feet (about 5 miles).

Comparing the Mackinac Bridge to Other Suspension Bridges

To give you context, the 3,800-foot main span places the Mackinac Bridge behind only a handful of US bridges. For example:

• Verrazzano-Narrows Bridge (New York): Main span 4,260 feet
• Golden Gate Bridge (San Francisco): Main span 4,200 feet
• Mackinac Bridge: Main span 3,800 feet
• George Washington Bridge (New York): Main span 3,500 feet

Internationally, it ranks outside the top 20, but it remains an engineering marvel due to its long total suspended structure and the challenging weather conditions it endures. The bridge's design accounts for high winds, ice, and temperature variations, making its suspension system both long and robust.

Why the Suspension Length Matters

The length of the suspension span directly affects the bridge's flexibility and load-bearing capacity. A longer span means lighter construction, but also greater susceptibility to wind and temperature changes. The Mackinac Bridge was designed to sway up to 35 feet in high winds to relieve stress—something you might notice if you cross during a storm. The 3,800-foot span also allowed for deep shipping channels beneath, which is critical for freighters moving iron ore and other goods through the Straits of Mackinac.

Practical Tips for Crossing the Mackinac Bridge

If you plan to drive across the Mighty Mac, here are some useful facts:

• Toll: As of 2025, the toll for passenger cars is $4.00 (cash or card).
• Speed limit: 45 mph for most vehicles, reduced in windy conditions.
• Length of crossing: At 45 mph, it takes about 8–10 minutes to cross the entire bridge, with the suspension portion taking roughly 2–3 minutes.
• Weather closures: The bridge may close or restrict high-profile vehicles when winds exceed 50 mph. Check the Mackinac Bridge Authority website for updates before your trip.

For pedestrians and cyclists, walkways are available only during special events (like the annual Mackinac Bridge Walk on Labor Day). Normally, only vehicles are allowed.

Frequently Asked Questions About the Suspension Span

Is the 3,800 feet the exact length? Yes, the center span between the two towers is precisely 3,800 feet. Measurements are from center to center of the towers.

How deep is the water under the suspension part? Maximum depth at the main span is about 250 feet, deep enough for large freighters.

Has the suspension length changed since construction? No, the span remains the same. The bridge has undergone cable wrapping and maintenance, but the dimensions are unchanged.

Final Recommendation

Now that you know the suspension part of the Mackinac Bridge is 3,800 feet long, you can impress your fellow travelers with this fact. If you're planning a road trip to northern Michigan, be sure to include a crossing of this iconic bridge. The drive offers spectacular views of the straits and the Great Lakes. For the best experience, cross during daylight and calm weather. And remember: the suspension span is just one part of a 5-mile wonder that has connected Michigan for over six decades.