Amazon has ordered 20,000 vans for its new delivery program in which contractors around the country can launch businesses that deliver packages for the online retailer.

The company said Wednesday that it increased its van order from 4,500 after it was surprised by the number of applications it received. The vans, which are stamped with Amazon’s smile logo in blue, can be used by contractors to deliver packages.

“We have been blown away,” said Dave Clark, Amazon’s senior vice president of worldwide operations. He said tens of thousands applied, but declined…