I am an amateur student of history. What we are living through these days has only one parallel in western civilization that I can see. That parallel is the Fall of Rome. Now Rome didn't exactly fall, so much as split into two Empires then crumble a quake a lot before melting away. There are valid arguments on both sides of the crash vs. slow decline when discussing both Rome and America. Until we actually have survived it we might have an answer. For now, let's all assume that either case is likely.
So let's see what Rome was like at the end of the 5th century AD.
There was a vast disassociation between the aristocracy and the Plebians (citizens). The ruling families that actually had a chance to be elected to the senate or maneuver themselves into the Throne were in their own world. Does this have a modern counterpart? Try to imagine the top 5% of either party having any sort of commonality with a middle-income or low-income American!
During the 2nd through 5th centuries, the military became more and more integrated, eventually resulting in a large portion of the Legions soldiers coming from German lands. This "Germanization" of the military was touted as one of the main causes for the fall of Roman Empire. Like Rome, the American military is a great way for someone to earn citizenship. At the end of the Empire, almost all of the Legions were "Barbarian." We are no where near that many foreigners in our military, but it is a trend worth noting. Another interesting tidbit is the Empire relied more and more on Mercenaries for their army. How many "defense Contractors" are employed in Iraq and Afghanistan? Another troubling trend is how street gangs join the military for training to use on the street.
There were many, many Barbarian invasions towards the end of Rome. Not to call the Latino Hordes 'Barbarians" but we have no border security. America is rapidly losing it's cohesive identity. Rome suffered similar problems. As the Huns pushed from Mongolia on the Eastern side, the Western borders let loose millions of immigrants into Rome. The Goths, Germanic Tribes. etc all made their homes inside the Empire. Like our immigration problem, these ancient immigrants did not mesh with the Roman Empire for many generations, weakening the bonds of community.
When the waves of immigrants from Europe came over they all learned English. Italian or German immigrants, it didn't matter. But now we have whole swaths of cities and whole regions of the country that do not speak, nor do they intend on learning English. Without a common language, it takes generations to intermix and fully identify yourself and your family as "American." From Cambodian neighborhoods in Lowell, to the Portuguese of Fall River, to the Cape Verdians in Dorchester, to the Brazilians in Sandwich, the many "Chinatowns" in major cities, or most of the southwest of the United States - no one will learn English.
How can we build a community if everyone acts like they are back home? I'm a New Englander, through and through. How many friends would I have if I kept talking and acting like one if I moved to Georgia? That's in the same country, and I'd be an outcast! now multiply that times many thousands. Until we integrate with a common language then we will continue to fracture like the Roman Empire.
Economic theories abound as well. Rome didn't produce many goods. The reliance on importing almost everything, along with the shortage of precious metals is another major contributing factor. Rome needed the metals to mint currency. As the available supplies of metals dropped, they used less and less silver and gold in their coins, which created inflation. For a modern equivalent, our inflation rate over the last decade was averaging above 5%. Like Rome, we don't export much anymore. With the exception of Debt, that is.
A more shocking economic parallel is that of the marginal farmer. In Modern terms think of these guys as small businessmen. The Senate needed to make more money, and Rome didn't have exports, so they raised taxes. Eventually, they raised taxes to the point that the marginal land couldn't be farmed except at a loss, so these farmers abandoned they lands and moved into the cities to eek out a living. Most could not. The Senate thought that the State needed to provide for those too poor to eat with a dole, very much like the American welfare and unemployment systems. How did they pay for these programs? By taxing those farmers who managed to stick to it, of course. Just like today, the Progressives in power make everyone else pay for these programs, while they use every loophole to get out of tier share of the burden.
The writing is on the wall for all to see. Unless there is a return to common sense in government, where the minority doesn't dictate to the majority. then we are a failed state that hasn't gotten around to falling flat on it's face.
There is some debate wether or not this Nation can be saved. I personally feel that it can, but it would require self sacrifice from every citizen. Tough love to those abusing the system. Addiction counseling for the debt-addicts of wall-street and middle America. This pervading sense of entitlement would need to be curtailed, sometimes forcibly. We would all have to be Americans, Americans without hyphens.