The campaign used AWS to avoid an IT investment that would have run into the tens of millions of dollars. Along the way they built and ran more than 200 applications on AWS, scaled to support millions of users. One of these apps, the campaign call tool, supported 7,000 concurrent users and placed over two million calls on the last four days of the campaign. Here’s a graph which depicts the growth in call volume in the days leading up to the election:
—Amazon Web Services Blog: AWS in Action - Behind the Scenes of a Presidential Campaign