"This country has endured far sharper divisions and not just endured but prospered and advanced."
Nonsense. The last time we had divisions this sharp it led to a Civil War that ravaged the nation for 4 years and cost us a million casualties. If our country were as segregated geographically by ideology, we'd have had a second civil war already, or at very least secession.
If it seems like nothing has changed, just remember, the Titanic floated for almost 2 hours after hitting the iceberg before it sank. In 2008 America ingested a fatal poison. In 2012 we failed to vomit it out.
The damage has been done, and it is impossible to tell whether we will survive it or not. But prosper through it? No, sir, we certainly will not prosper.