Tourism has become the main industry in recent decades. In 2005, ShermanTravel, LLC listed the Upper Peninsula as #10 in its assessment of all travel destinations worldwide. The peninsula has extensive coastline on the Great Lakes, large tracts of state and national forests, cedar swamps, more than 150 waterfalls, and low population densities. Because of the camping, boating, fishing, snowmobiling, hunting, and hiking opportunities, many Lower Peninsula and Wisconsin families spend their vacations in the UP, and tourists visit from Detroit, Chicago, Grand Rapids, Milwaukee, and other metropolitan areas. The opening of the Mackinac Bridge in 1957 (see below) has made the Upper Peninsula easily accessible to tourists from the Lower Peninsula and southeast of Michigan, and has helped make the UP a year-round tourist destination.