Naturalization ceremony at the National Archives (5 images)

Naturalization candidates raise their hands and pledge the Oath of Allegiance during a ceremony for new U.S. citizens at the National Archives in Washington, D.C. on December 15, 2015. Pool photo by Martin H. Simon/Pool

U.S. President Barack Obama speaks beneath a painting of America's founding fathers during a naturalization ceremony for new U.S. citizens at the National Archives in Washington, D.C. on December 15, 2015. Pool photo by Martin H. Simon/Pool

A naturalization candidate displays her American flag and Oath of Allegiance as the roll is called during a ceremony for new U.S. citizens at the National Archives in Washington, DC on Tuesday, December 15, 2015. Thirty-one candidates from 25 countries took part in today's event, which marked the 224th anniversary of the Bill of Rights. U.S. President Barack Obama spoke at the ceremony. Pool Photo by Martin Simon/UPI

U.S. President Barack Obama speaks beneath a painting of America's founding fathers during a naturalization ceremony for new U.S. citizens at the National Archives in Washington, DC on Tuesday, December 15, 2015. Pool Photo by Martin Simon/UPI