In the 1800s, the main job requirement for most federal employees was loyalty to the newly-elected president, who would fill the government bureaucracy with his supporters. But after a rejected office-seeker shot President James Garfield, reformers won long-sought-after changes: workers hired for their expertise, not their fealty. Correspondent Mo Rocca talks with journalist and historian Scott Greenberger about how a meritocracy finally came to the federal government, and finds out what Mark Twain had to do with it.