Michael Lind had a great thesis
in Salon last week about the three phases the United States have gone through, and the fourth that's begun. In essence, each phase lasts 72 years, even though that sounds like numerological voodoo.
The first half of each phase, or Republic in the French manner, is a Hamiltonian nation-building period, which is then followed by a Jeffersonian limited-state backlash (note that Jefferson himself wasn't particularly Jeffersonian by this analysis!).
Each Republic is associated with a new period in technology, and they begin with a heroic President and end with a dire one. So...
First Republic: 1788 - 1860
First half: President: George Washington and the Federalist Party build a federal state.
Second half: Backlash led by Andrew Jackson, era ends with James Buchanan and America on the eve of the Civil War
Second Republic: 1860 - 1932
First half: Abraham Lincoln reunites the country by force, the end of slavery and Reconstruction, builds railroads and other infrastructure.
Second half: Backlash led by populists, culminates in Hoover and the Wall St Crash
Technology: Coal, steam, and then Fordism.
Third Republic: 1932 - 2004
First half: Franklin D Roosevelt's New Deal, economic regulation, more infrastructure, end of segregation
Second half: From Nixon onwards, attempts to cut taxes and the size of government, culminating in second Bush presidency
Technology: electricity, internal combustion engine, new media
Fourth Republic: 2004 - 2076??
First half: Barack Obama..
And then the crystal ball is hazy, although it projects constructive expansion of government - healthcare, clean power? - led by Obama, with a backlash starting precisely in 2040. The clock's ticking.
In my optimistic moments I have said that if Obama lives up to his promise he could indeed be one of the four most important American Presidents to date: the three identified by Lind in this article were the other three I had in mind. Whatever their flaws, it's hard not to see the current United States as primarily shaped by those three, and however implausible the 72-year Republics sound, it's an interesting analysis.