At the Democratic National Convention, the youngest mayor of a top 50 U.S. city – San Antonio Mayor Julian Castro – presented the keynote speech.

The first Hispanic keynote speaker at a Democratic convention, the 37-year-old is being compared to Barack Obama, who was relatively unknown before he presented the keynote at the 2004 Democratic National Convention.

Seven years ago, Radio-Television-Film chair and documentary filmmaker Paul Stekler chronicled Castro's mayoral campaign.