A big explosion sends the final two sections of the westbound Blanchette Bridge into the Missouri River. Crews used explosives Tuesday to take down the sections of the bridge that connects St. Louis and St. Charles counties along Interstate 70. The work is part of a $63 million rehabilitation project. (KMOX/Brett Blume)

ST. CHARLES, Mo. (KMOX) – A six-decade old section of the Blanchette Bridge is no more.

With a tremendous blast, more than 1000-feet of the Old Blanchette Bridge connecting St. Louis and St. Charles Counties tumbled into the Missouri River below.

• Check out more photos from the bridge explosion

Tuesday morning’s demolition was the second and last needed to bring down the 54-year-old structure, to make way for a new span.

The westbound span closed Nov. 4 and will reopen next fall. For now, all traffic has been rerouted to the eastbound span.

About 1,000 people gathered to watch the bridge explosion. About 4.5 million pounds of steel dropped into the river, creating waves that crashed into the riverbank.