Our taxes barely cover our social-welfare programs; everything else is on credit.

All federal revenues—from income taxes, Social Security and Medicare payroll taxes, corporate taxes, excise taxes, customs duties, estate and gift taxes and user fees—are consumed to pay Americans myriad federal benefits. These include Social Security, Medicare, Medicaid, veterans' benefits, food stamps, farm subsidies and the many other forms of social insurance and welfare, including economic stimulus and job-creation.

Put another way: The federal government borrows everything it needs to operate what we ought to think of as the government as an institution, such as defense (including the support of troops in Afghanistan and Iraq); highway construction; foreign aid; aid to states and localities; land management and pollution control; regulation of this, that and all the other things; scientific research; payment of federal employees' salaries; and payment of interest on the national debt.

http://online.barrons.com/article/SB50001424052970203703404576291230749135162.html