The Metro in the nation's capital, was hobbled after an electrical malfunction filled a L'Enfant Metro subway station with smoke on Jan. 13, 2015, killing one woman and sending dozens of people to hospitals. Pablo Martinez Monsivais/AP hide caption

itoggle caption Pablo Martinez Monsivais/AP

Members of the Mexico team celebrate a 4-2 win against the United States in the CONCACAF Gold Cup soccer final at the Rose Bowl in Pasadena, Calif., June 25, 2011. Jae C. Hong/AP hide caption

itoggle caption Jae C. Hong/AP

Chromosomes and double helix over silhouettes of man Lee Woodgate/Ikon Images/Getty Images hide caption

itoggle caption Lee Woodgate/Ikon Images/Getty Images