From the Associated Press — More than 100 antique snowmobiles are expected to cross the Mackinac Bridge as part of the fourth annual Snowmobile the Mac. MLive.com reports the event will be held December 14. Snowmobiles will cross the bridge from Mackinaw City in Michigan’s Lower Peninsula to St. Ignace in the Upper Peninsula. The St. Ignace Chamber of Commerce says the event started in 2016 with 38 antique snowmobiles. Snowmobiles must be at least 25 years old and have wheel kits to keep their treads off the bridge pavement. Operators must register their snowmobiles in advance and gather the day of the event in the Colonial Michilimackinac parking lot in Mackinaw City.