The Mackinac Bridge is currently the seventh-longest suspension bridge in the world by total suspended length, and the longest suspension bridge in the western hemisphere. The bridge opened to traffic on November 1, 1957. The following facts and figures are quoted from David Steinman’s book “Miracle Bridge at Mackinac”.
LENGTHS
| 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. | 8,614 Ft. |
| Total Length of North Approach | 7,129 Ft. | 2,173 Meters |
| Length of Main Span (between Main Towers) | 3,800 Ft. | 1,158 Meters |
HEIGHTS AND DEPTHS
| 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 |
CABLES
| 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 |
WEIGHTS
| Total Weight of Bridge | 1,024,500 Tons | 929,410,766 kg |
| Total Weight of Concrete | 931,000 Tons | 844,588,992 kg |
| Total Weight of Substructure | 919,100 Tons | 326,931,237 kg |
| Total Weight of Two Anchorages | 360,380 Tons | 326,931,237 kg |
| Total Weight of Two Main Piers | 318,000 Tons | 288,484,747 kg |
| Total Weight of Superstructure | 104,400 Tons | 94,710,087 kg |
| Total Weight of Structural Steel | 71,300 Tons | 64,682,272 kg |
| Weight of Steel in Each Main Tower | 6,500 Tons | 5,896,701 kg |
| Total Weight of Cable Wire | 11,840 Tons | 10,741,067 kg |
| Total Weight of Concrete Roadway | 6,660 Tons | 6,041,850 kg |
| Total Weight of Reinforcing Steel | 3,700 Tons | 3,356,584 kg |
RIVETS AND BOLTS
| Total Number of Steel Rivets | 4,851,700 |
| Total Number of Steel Bolts | 1,016,600 |
DESIGN AND DETAIL DRAWINGS
| Total Number of Engineering Drawings | 4,000 |
| Total Number of Blueprints | 85,000 |
MEN EMPLOYED
| Total, at the Bridge Site | 3,500 |
| At Quarries, Shops, Mills, etc. | 7,500 |
| Total Number of Engineers | 350 |
IMPORTANT DATES
| Mackinac Bridge Authority Appointed | June, 1950 |
| Board of Three Engineers Retained | June, 1950 |
| Report of Board of Engineers | January, 1951 |
| Financing and Construction Authorized by Legislature | April 30, 1952 |
| D.B. Steinman Selected as Engineer | January, 1953 |
| Preliminary Plans and Estimates Completed | March, 1953 |
| Construction Contracts Negotiated | March, 1953 |
| Bids Received for Sale of Bonds | December 17, 1953 |
| Began Construction | May 7, 1954 |
| Open to traffic | November 1, 1957 |
| Formal dedication | June 25-28, 1958 |
| 50 millionth crossing | September 25, 1984 |
| 40th Anniversary Celebration | November 1, 1997 |
| 100 millionth crossing | June 25, 1998 |