With many state and local agencies unable to fully fund their retirement benefits, some states' debt is mounting beyond that of entire nations. According to the OECD's most recent debt-to-GDP rankings, Estonia had the lowest debt at 13% of GDP, or a total of $2.5 billion. As you'll see, each state on this list has far more debt than Estonia, and for some, more than several other countries too. Read on to find out which states are heavily in the red and how much they owe, according to the Census Bureau’s most recent figures.