阅读理解
For decades, ferry boats crossed the cold waters of Michigan's Straits of Mackinac, shuttling people and vehicles between the two halves of the split-up state. Since the 1880s, Michigan residents dreamed of a bridge that would span the 4-mile gap between Mackinaw City and St. Ignace, an area that limited tourism in Mackinac Island and disturbed commerce in the remote Upper Peninsula. Because construction would be hard, with high winds and harsh winters, some engineers suggested a floating tunnel or a series of small bridges instead. But, by the 1940s, with lines for ferry boats sometimes stretching for 16 miles, the idea of one continuous span won out. And what a span it turned out to be. Five miles long, the "Mighty Mac," which opened to traffic on Nov. 1, 1957, was to become the world's longest suspension bridge between cable anchorages. Even today, it remains the longest suspension bridge in the Western Hemisphere and the third-longest bridge in the world. Designed by engineer David B. Steinman, the bridge was built in just three years, on time and on budget. That was a remarkable feat in itself. But the challenges were so great—33 of the bridge's 34 pieces had to be built under water—that five workers perished during construction. One man died diving, one fell in a caisson while welding, another drowned, and two fell from a catwalk. The bridge has seen many tragedies since. On Sept. 10, 1978, three National Guard officers in a private plane got lost in a thick fog and crashed into the cables of the north tower. In 1989, a woman was killed when gale force winds—and her excessive speed—lifted her 1987 Yugo into the air, sending it 150 feet into the water. And in 1997, a sport utility vehicle took the plunge. Although authorities believed the latter incident to have been a suicide, the bridge does not attract jumpers the way, for instance, the Golden Gate does. In 1977, Lawrence Rubin of the Mackinac Bridge Authority shared his theory on the lack of leapers with the Detroit News: "People who commit suicide like attention. But it's peaceful here... you could jump off this bridge, and it might take years before anybody found out." The bridge authority acknowledges that the prospect of such excitement may be overwhelming for some, which is why it offers free escorts for gephyrobiacs—people with a fear of crossing bridges. Each year, hundreds of drivers take advantage of the service.
单选题1.According to the first paragraph, Michigan's Straits of Mackinac