Final answer:
Mass shooting casualties from 2000-2013 were a significant concern in the United States, with high-profile incidents occurring at schools and other public places.
Step-by-step explanation:
Mass shooting casualties in the years 2000-2013 have been a significant concern in the United States. Between this period, there were several high-profile shootings that took place at schools and other public places. For example, the Columbine High School shooting in 1999 and the Sandy Hook Elementary School shooting in 2012 highlighted the issue of gun violence and its impact on society. These incidents sparked debates about gun control and access to firearms.