Zach Brown's preferred mode of transportation is his skateboard. Brown, 27, is an artist and actor who doesn't own a car. Courtesy of Zach Brown hide caption

itoggle caption Courtesy of Zach Brown

Teenagers turn to their phones and social media to find rides. Tanggineka Hall/Youth Radio hide caption

itoggle caption Tanggineka Hall/Youth Radio

Donta Jackson's snack of choice is a bag of Skittles. Brett Myers/Youth Radio hide caption

itoggle caption Brett Myers/Youth Radio

Young debaters at the Bay Area Urban Debate League in Oakland, Calif., say that there are a lot of differences between the way that they debate the issues and what they see the presidential candidates doing on debate nights. Jenny Bolario/YouthRadio for NPR hide caption

itoggle caption Jenny Bolario/YouthRadio for NPR

Alejandra Salinas, president of the College Democrats of America, says the group's numbers have been growing in key states like Florida and Ohio. Brett Myers/Youth Radio for NPR hide caption

itoggle caption Brett Myers/Youth Radio for NPR

Young supporters attend the Republican National Convention in Tampa, Fla. At 42, Paul Ryan is the first member of Generation X to join a presidential ticket. Spencer Platt/Getty Images hide caption

itoggle caption Spencer Platt/Getty Images

Dr. Amit Etkin and a research assistant help a participant into the bore of the MRI. Courtesy of the Etkin Lab at Stanford University hide caption

itoggle caption Courtesy of the Etkin Lab at Stanford University