It's a big day for the Mackinac Bridge.

The suspension bridge that connects Michigan's Lower and Upper peninsulas opened to traffic Nov. 1. 1957, which means today is its 60th birthday. In honor of the big day, here are 60 facts that you may or may not know about about the bridge, many courtesy of the Mackinac Bridge Authority.

1. The Mackinac Bridge is the fifth-longest suspension bridge in the world.

2. Its main span is the 19th longest in the world.

3. The bridge opened to traffic on Nov. 1, 1957.

4. Its total length is 5 miles, or 26,372 feet.

5. The main towers are 552 feet above water.

6. The roadway is 199 feet above water at midspan.

7. There are 42,000 miles of wire in the main cables.

8. The cables weigh 11,840 tons.

9. The total bridge weight is 1,024,500 tons.

10. That weight includes 931,000 tons of concrete.

11. it has 4,851,700 steel rivets.

12. And 1,016,600 steel bolts.

13. Four thousand engineer drawings were done for the bridge.

14. There were 85,000 blueprints.

15. 3,500 workers were employed at the bridge site.

16. 7,500 workers were employed at quarries, shops, mills, etc.

17. 305 engineers were employed

19. At the time, it was the largest bridge construction fleet ever assembled.

20. Construction began on May 7, 1954.

21. The 50 millionth crossing took place Sept. 25, 1984.

22. The 100 millionth crossing took place June 25, 1998.

23. D.B. Steinman was selected as its engineer in January 1953.

24. Five men lost their lives during construction.

25. One man died in a diving accident.

26. One man fell in a caisson while welding.

27. One man fell in in the water and drowned.

28. Two men fell from a temporary catwalk near the top of the north tower.

29. On Aug. 7, 1997, a bridge painter, fell from his painting platform and drowned in the Straits of Mackinac.

30. The length of the man span is 3,800 feet.

31. The width of the bridge's roadway is 54 feet.

32. The outside lanes are 12 feet wide.

33. The inside lanes are 11 feet wide.

34. The center mall is 2 feet wide.

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