The 2012 presidential race was not only the most expensive in history, it was also one of the most closely contested elections the country has known. President Barack Obama inherits the very serious challenge of trying to reunite a divided nation in which political paralysis has seemingly become the frustrating and often destructive new normal. It’s a tall order, but history tells us this problem is not insurmountable.

The challenge is, for all the talk about his interest in history, Obama has so far failed to draw on the most salient leadership lessons of his predecessors.

When Obama was elected in 2008, comparisons to Abraham Lincoln and John F. Kennedy were often invoked. Yet if the problem ahead of him is indeed to be surmounted, it will be because he finally truly looks back to these tight presidential races of the past and what the victors did after taking office as he prepares for his second term.

The elections of 1860 and 1960 were both close, divisive contests. And the winners, Abraham Lincoln and John F. Kennedy, each took the Oath of Office amid collective discord and anxiety, much like today. Also like today, Lincoln and Kennedy both won the Electoral College with room to spare, though not one of the three presidents claimed a strong majority of the popular vote....