When Ronald Reagan took office in 1980, the US national debt stood at around $2tn. By 2011, it stood at a staggering $15tn and has become one of the most significant problems in American politics. It has revealed the deep ideological splits that run right across the US political landscape and now threaten the health of the entire US economy. Reported over the decades by the Guardian's finest journalists, this is the modern story of America's national debt.