One thing that locking up a couple of million people gets you is a chunk of the economy dependent on keeping people locked up. The American prison system is massive. So massive that its estimated turnover of $74 billion eclipses the GDP of 133 nations. In many areas—especially areas where other parts of the economy are weak—towns and cities have actively courted the construction of big prison complexes and expansions of local jails, treating the incarceration of thousands of fellow Americans as dependable source of income.