What government job has the most travel?

I want to make a career change. I have heard that there are many government jobs that allow travel nationwide to work assignments. I have a bachelors in criminal justice but don't want anything law enforcement or military based. I looked into FEMA's reservist format and liked it but not looking for them now. Would other DHS agencies or even the FBI have anything like this? I do like field (non-office) work as much as possible.