DETROIT — Electric vehicle startup Rivian Automotive got a big boost from one of its investors on Thursday when Amazon.com announced it was ordering 100,000 electric delivery vans.

Before Rivian has even begun commercial production at its factory in Normal, Illinois, the Amazon order rocketed it to the forefront of electric vehicle makers.

Amazon Chief Executive Jeff Bezos said in Washington that as part of the online retailer’s plan to be carbon neutral by 2040 it would order the electric vans from Rivian, with deliveries starting in 2021. The goal is to deploy all the vehicles by 2024.