Several Factors Have Historically Extended the Lifespan of a Civilization

Sadly, by markers of a true civilization (a food surplus, strong cities, labor specialization, empowered and convincing religion, effective social and economic organizations, and an organized government) the United States has failed. Historically, what are most important elements that distinguish civilizations that survived in the past? Natural barriers against invaders; Reliable agriculture, predictable harvests, fertile and abundant soil; Self-sufficiency, less need for imports; and a Central, respected/feared government. All of these elements no longer exist. As with Durant's prediction, the United States has destroyed itself from within and awaits destruction from without, as did Rome. Causes: fleeting relative wealth, sloth, rampant crime, individual's self-absorbed and greedy, corruption accepted at all levels, failed educational system, individual and group false expectations.