“Cash for Clunkers,”—the program that rewards people for trading in their gas guzzlers for newer, more fuel-efficient vehicles—is running out of cash after only a few days in operation. The program, originally funded at $1 billion was supposed to last until November 1. This news makes us wonder: Has the government ever seriously underestimated the cost of a government program before? Why yes! In a recent bulletin for the Cato Institute, Michael Tanner and Chris Edwards write:

When Medicare was launched in 1965, Part A was projected to cost $9 billion by 1990, but ended up costing $67 billion. When Medicaid’s special hospitals subsidy was added in 1987, it was supposed to cost $100 million annually, but it already cost $11 billion by 1992. When Medicare’s home care benefit was added in 1988, it was projected to cost $4 billion in 1993, but ended up costing $10 billion.

The Congressional Budget Office and the White House have been tussling over the cost of health care reform legislation; but if history is any guide, they’re probably both underestimating the costs.