This seems like a good time in history to talk about the FBI.
It has taken its share of dents and dings of late, but there's a compelling reason for a national police force. Before 1933, police could not easily chase bank robbers and other criminals across state lines.
Journalist Joe Urschel writes of that year and the changes it produced in The Year of Fear: Machine Gun Kelly and the Manhunt That Changed the Nation. We revisit Joe Urschel's visit from October 2015.