Mackinac Bridge: Status, History, and Maintenance

The Mackinac Bridge ("Mighty Mac") is not under construction. It opened to traffic on November 1, 1957 after 42 months of building.

Bridge Specifications

• Total length: 26,372 ft (5.0 mi / 8.0 km)
• Main span: 3,800 ft (1,158 m) — longest suspension span in Western Hemisphere
• Towers: 552 ft (168 m) above water
• Roadway: 200 ft (61 m) above water at midspan
• Lanes: 4 (2 each direction); no shoulders

Maintenance Program (Ongoing Since Opening)

• Annual painting: 7-year cycle; 100% zinc primer + epoxy + urethane topcoat
• Cable inspection: Main cable unwrapping, dehumidification (installed 2000s)
• Deck replacement: 1990s (original grating → concrete); periodic joint repairs
• Structural monitoring: 300+ sensors (strain, wind, temp, corrosion)
• Ice management: Falling ice protocols; closures rare but occur

Recent Major Projects

• 2017–2020: $55M cable dehumidification & band replacement
• 2021–2023: $28M deck resurfacing & joint replacement
• Annual: ~$5–8M routine maintenance

Traffic & Operations

• 4–5M vehicles/year (seasonal: summer 2× winter)
• Toll: $4/car (2024); MAC Pass electronic tolling
• High wind closures: >50 mph sustained / >65 mph gusts
• Annual Labor Day Bridge Walk (since 1958) — only pedestrian day

Common Confusion

Ongoing maintenance (painting, deck work, cable care) is sometimes mistaken for "construction." The bridge is complete; preservation is perpetual for a 5-mile suspension span in a harsh Great Lakes environment.