ST. IGNACE, MI (AP)-- Traffic across the Mackinac Bridge has increased over the past year.
The Evening News of Sault Ste. Marie reported Saturday that more than 3.9 million vehicles used the span in 2015 to cross between Michigan's Upper and Lower peninsulas.
More than 3.6 million crossed the bridge in 2014.
Mackinac Bridge Authority Executive Secretary Bob Sweeney says "the improving economy is likely the largest factor driving this increase in traffic."
Sweeney also pointed to low fuel prices, bridge special events and travel advertising as contributing to the uptick.
The authority gets its funding from bridge tolls and fees. The revenue is used to maintain, operate and protect the 58-year-old structure.
Sweeney says $180 million in preventive maintenance work is scheduled over the next decade.
