From pages 140-41 --
Two critical components of modernity shared by the North and the South -- print and popular politics -- created the necessary contexts for the war. Print permitted people to cast their imaginations and loyalties beyond the boundaries of their localities, to identify with people they had never met, to see themselves in an abstract cause. People learned to imagine consequences of actions, to live in the future.
Print shaped everything we associate with the coming of the Civil War. Although Bleeding Kansas was far removed from the East and John Brown's raid freed no slaves, these events gained critical significance because they were amplified and distorted by newspapers. Without the papers, many events we now see as decisive would have passed without wide consequence. With the papers, events large and small stirred the American people every day. The press nurtured anticipation and grievance. Americans of the 1850s grew newly self-conscious, deeply aware of who they were and who others said they were. The "North" and the "South" took shape in words before they were unified by armies and shared sacrifice.
It was surely no accident that a long-brewing sectional animosity boiled over when railroads, telegraphs, and newspapers proliferated in the 1840s and 1850s. Suddenly, local bargains and gentlemen's agreements in Washington could not stand. Politicians could no longer get away with saying one thing in one place and something altogether different somewhere else, for their speeches raced ahead of them by telegraph and newspapers. Rival editors wrenched the most inflamitory words out of context, underlining their danger, amplifying their threat.
There's more, but you get the idea, hopefully.