Authorities say a piece of metal on a seam popped on the George Washington Bridge Tuesday night, flattening tires on nearly 20 cars and closing two lanes of traffic.

The Port Authority of New York and New Jersey says the finger joint popped up on the inbound upper level of bridge, which spans the Hudson River.

The joint allows the bridge's roadways to contract and expand in hot and cold weather.

While it was not immediately clear what caused the joint to become exposed, it is now believed that the glitch was caused by, what has been described as, extensive wear and tear.

The agency said crews fixed the problem by 2:30 a.m. Wednesday.

More than 100 million vehicles cross the bridge every year.